Enamel on Steel – some insights

I commonly get emails asking for hints on how to enamel on steel. I have a little bit of experience – enough to make me dangerous you might posit – so I thought I might dump what little I know here to save anyone interested the time it might take me to respond to an email inquiry. But first…

New NEWS!!

April 2017

WG Ball have updated their offerings of enamel for steel, and the picture look great, and they now offer a wonderful range of colours in a single sample set! It looks very fancy – the grey, jade and yellows have really taken my eye – and they have a ground coat that looks like a good bet too. If you have any, please let me know what you think!

2015

Thompson Enamel have updated their website! It’s not any more user friendly, but it is more modern looking. Swings and roundabouts, eh? Anyway, it means that all of my links need updating. Never fear, they will be done, in time. In the mean time, this is the new link for Ground Coat for enameling iron – the infamous GC-16. Use it wisely!

I’ll be sure to update y’all *here* when I have the other links sorted.

Update Sept 2014: I’m back from Erfurt! More artists have been getting in on the action on the HE blog, so be sure to check that out as it develops. I made some interesting new discoveries with the exceptional enamels on hand there, and I can now say with confidence that you can easily fire a first coloured layer direct to the metal, if you have enough enamel experience/quality enamel to work with… (Still not sure which is the most important factor there.) Also, we were firing on the high side of 800*C/ 1472*F, so don’t be afraid if the temperatures are getting up there (admittedly though, I was working in 1.5mm thick – 14 gauge – .064″ -steel which is pretty heat needy).

The other thing I learned? The coefficient of expansion really gets you on bigger pieces of steel, as you might expect. I needed to coat the back of my pieces of stainless steel to stop them bowing, and then potentially throwing pieces of enamel. Up until this point I had fired smallish objects, nothing over about an 8cm x 8cm (~ 3″x3″) square, which I’ve found can hold its own against the amount of enamel stress attacking it from the obverse side. When you get bigger than that it does start to warp your metal. That’s fine, if you don’t mind bowed metal, but after a few layers it will start to crack the enamel you’re working on. So, lesson learned. As all the books say, you should add a counter enamel layer to keep warp-age and ping-age in check.

Important news!!

I’ve cracked the code! This is Thompson Enamel’s ground coat:

 GC-16 COBALT BLUE Ground Coat for Enameling Iron

Also known throughout this article as Grip Coat and otherwise known as undercoat. This enamel, when applied as a base layer, has metal oxides to help it really meld with the metal, and being an enamel it works well with the other enamels you want to apply over the top. This is the one that really wants to stick to the steel so I use it especially when using poor-grade (read – high carbon) steels. And don’t forget the WG Ball version too.

||| OK, now back to the scheduled programming |||

To enamel on steel, you need some enamel, and some steel. Liquid enamel, known in the US as porcelain enamel, is what I have been taught to use, and I have found that when using this the process of getting it to stick to any grade of steel reasonably universal, though obviously the more suitable grades (low-carbon steel typically used as the base material in architectural/signage applications as one example) are generally easier to enamel, and are more resilient. Like any metal choice the material is of course application specific, so say you plan to enamel only one side and show the works outdoors, I would suggest an exterior grade stainless, but indoors? The steel world is your oyster. I have found that you can get enamel to work pretty well for both stainless and mild steels, so long as you do the right preparation.

enamels
In the past I have ordered my enamels from two different companies, Thompson Enamel from the US, and WG Ball from the UK. There are others who you might be able to find, but these can be bought direct or from on-sellers both locally and in other countries. Both Thompson Enamel and WG Ball sell dry forms of ‘liquid enamel‘ that you can purchase and add water to yourself, which is useful if you’re not on their home-continent.

Why is it called liquid enamel when what you get is powder? Liquid enamels are often delivered as a very fine powder, which is incidentally much finer than regular jewellers enamel (which my enamel guru Elizabeth Turrell calls ‘sifted enamel’.) Jewellers enamel is a much coarser grit, as it will fit through a 60-80 mesh, whereas industrial or liquid enamel will fit through a much finer 200 grade mesh. (So putting regular enamel in solution will not achieve the same end.) So when you receive your enamels, chances are you will have to add the water. (If you’re in the US/UK, you can order them in solution, which I have been advised is the best way to go. Obviously shipping weight is a bigger factor in ordering internationally, as are freezing temperatures in winter as I recently learned via Ganoksin.)

You do have to ensure that you get the right enamel, so that it will accept water. On the Thompson website goes under the name of both Liquid Enamel and Brushable Enamel, while on WG Ball they are called Wet Process enamels (for steel.) Thompson also sell tonnes of other types, including things like enamel crayons which are fun to use over the top of a fired surface.

When adding water to the enamel I have found it best to treat it a bit like making a batter, stirring while adding a little water at a time, until you get it to the right consistency. I sometimes get impatient, and think I’ll just add a bit more liquid this round, and I inevitably end up with it too runny.

What’s right? Well, it depends on what you’re doing, but pancake (perhaps crepe?) mix to (pouring) cream or even milky consistency is good. It’s good to give it some time for  it to rest before you start using it, and of course it settles between uses, so always be sure to stir it before using. And as ever, have some metal around for testing. Ganoksin has a great in-depth guide on how to mix, which includes data on good ratios of enamel to water. Thompson very astutely also includes a pamphlet with their enamel orders that show how to mix their product.

metal
I have used sandblasted recycled tin cans, washers, pristine stainless panels and sundry other objects in my works and tests, so my advice is that if you can prepare a steel surface correctly, you can probably enamel on it. A sandblasted steel can (known as a tin can in the US and Australia) of the ilk that you get your canned veg in (big tomato tins are great) is a great test material. There’s also an enamel product called Grip Coat /Groundcoat that can help you with using low-grade steel, which you can lay down as a first layer and fire before adding your other layers, and which bonds beautifully to just about any steel and other enamels.

Melissa Cameron. Ray, 2012. Stainless steel, vitreous enamel, 925 silver fixings.

You do have to be careful with mild steel, in that using a wet enamel will start to oxidise (read rust) your pieces in some situations. This can be a great thing to promote, but if you’re after a pristine surface it’s something you will have to keep track of. The small yellow streak to on the right hand section of the work above is a rust stain starting to develop from the fired stainless steel wires. Yup, even stainless can sometime turn on you, because of the temperatures involved. I happened to like the stain, so I then had to carefully cultivate it through other firings…

I’ve also been collecting rust from some pieces of mild steel for a while now too, to try as a pigment, so I’ll keep you updated on what happens. (*update #1 at end.) If you’re inclined, start collecting copper fire-scale, since it can give lovely green tones too.

This mild-steel recycled object work (below) looks fairly brown, as the transparent enamel shows exactly what is underneath it – steel. Steel blackens when fired, so you need to remember that when using transparent – including transparent base coats – as the first layer. This has Thompson Low Fusing transparent, the medium fusing tends to come up a bit cloudier and so the colour goes from what is here, a real black-brown, to a more fawn-green-brown. In this case it worked well with the piece, so well that although I had planned on texturing it I decided that I liked it and left it shiny instead.

Melissa Cameorn, Infinity Affinity, 2011. Saw pierced steel baking dish, vitreous enamel, 925 silver, stainless steel

If you want a good steel surface, you need to look for a low carbon steel. Once in the kiln, carbon of a lesser quality steel will form gas bubbles that come up through the enamel. Right here a quote from the master, Elizabeth Turrell, is in order:

“Mild steel that is higher in carbon sometimes results in gas bubbles and poor adhesion of the enamel to the steel, (any gas bubbles can be rubbed back, worked over etc) but it is easier and cheaper to buy in small quantities or beg it from metals shops.

However, the key is adhesion of the enamel to the surface after each firing and once the work is finished. (No popping off as you walk away!) Metal preparation / sand blasting is essential for reliable adhesion. Always make sure you wipe any residue of the sandblaster material off the metal before enamelling, other wise you will get pinholes on the fired surface. If you have no access to a sandblaster, an electric grinder [sander] will give you a surface that the enamel will adhere to.”

I’m not as optimistic about a metal grinder getting a toothy enough surface, and I typically caution against using acid to etch the surface of the steel for same, mostly because the acids that attach steel are particularly nasty. What you need is what I call a consistently inconsistent surface to work on, which the sandblaster using high pressure and aluminium/aluminum oxide or garnet blast media do best. See the best practice used by Arcelor Mittal in its Steel for Enamelling and Enamelled Steel User Manual if you’re interested in how industry goes about the process.

metal preparation

Like the lady said, sandblast it. Using a reasonably coarse grit (aluminium oxide, or garnet if it comes to that) sandblast the surfaces to be enamelled. Be sure to wipe off the residue once you pull it from the sandblast cabinet, because as per Elizabeth’s quote, this will stop proper bondage of the enamel to the metal surface.

If you don’t have a sandblaster, never fear, you can rough up the surface in other ways. Try detergent and leftover enamel (take precautions, you’re dealing with glass and you might need your fingerprints afterwards) or a coarse sandpaper. Or, purchase (or find) pre-enamelled panels to which you can add more enamel. Thompson sell a range of pre-enamelled sample squares, though there are plenty of places to get pre-enamelled objects to work with.  When I was in the studio in Bristol an artist was working on translating a bunch of drawings from some children (he was working on a commission for a primary school) onto a bunch of oven panels. Yup, old white oven walls, doors and the like. Properly cleaned these pre-enamelled panels are a great surface on which to add more enamel. No need for a ground coat and they take liquid and sifted enamels over the top of the base coat really well. So if you were planning to use recycled metal (a little hard to cut, I’ll grant you) you can work straight over something already enamelled with regular jewellers enamel. The cleanup before firing in this case is the hard part, especially on an old oven…

Whiteboards are enamelled, as are camping mugs and plates. And if you happen to have access to a decent cutter/guillotine, it is possible to put some masking tape down and slice through a pre-enamelled panel. I’ve seen it done, though once again, shards of glass are… well, shards of glass! I’ve heard tell of artists who use snips (carefully) on the whiteboard panels to shape them, not to mention actually saw piercing. Both things I’m yet to try, but sound plausible.

recycled steel

If you are going to used recycled steel, be aware that it may be coated. And if that coating is something like galvanisation, ie. zinc, be really careful. Make sure you get totally through that layer with the sand blaster, as zinc poisoning from being fired in a kiln is life threatening.

Removing a galvanized surface - the zinc is the lighter coloured material. This needs to be totally removed before the piece is ready to be enamelled.
Removing a galvanized surface through sandblasting – the zinc is the lighter coloured material on the outside of that blasted ring, while the darker and duller grey in the centre is the natural steel. The zinc needs to be totally removed before the piece is ready to be enamelled, or in fact heated in any way.

A good question came in from a reader, so good that I’m reposting the answer here (thanks Lisa H!) How do you diagnose galvinised steel?

Good question, how can you tell if something is zinc plated? Well, it takes some practice, and for you to look for some telltale signs. Zinc plating looks brighter than normal steel or can sometimes comes in a brassy finish. It will generally show no signs of rust (which is pretty rare in a magnetic piece of steel) and will be a lighter grey colour than a true steel grey. You have to spend a bit of time looking at variations in the greyness of steel before zinc will pop out as an intruder, but if there’s any doubt, try taking some of the coating/outer layer off to see what the underlying metal is.

application
The trick with enamelling steel is a thin first layer. Very early on I learned that if I did too thick a layer with an object I was working on the layer of enamel would literally jump off the steel. (This can also happen when the metal preparation is not quite biting enough.) It pings the fired glass in small shards, which littered the surface of the bench I was at. Messy and a little bit dangerous (I’ll say it one more time, it is glass…) So, depending on the object (and some shapes or enamels are just more likely to ping so you have to put in extra effort with them), it is possible to put on a thin layer of enamel (I use clear, I have found heavily pigmented enamels, red, for instance, to not be a friend in these delicate first layer scenarios) over steel and have it stick, but the trick is thin. But not so thin so as to have the coverage be broken.

Remember that unlike copper, counter enamelling the panel/object is not so important. You can build up the front without having to build up the back quite so much. The strength of the steel is your friend. If I do a backing layer it’s generally for decorative purposes, unless the work is big and heavy with enamel layers, as the enamel can still make steel warp.

buying enamels
There are great local places for enamel too – Koodak in Melbourne, Australia has started stocking liquid enamels, so look local. Below I have listed what I have (as at July 2012). You do have to  remember, as with any enamel on metal, the clears will give you the base colour of the fired metal underneath. With steel, that is often very close to black, or a smokey grey if you’ve really layered up the enamel. So translucent colours might need a base layer of white under them, and very often this is also a suitable first layer as it’s relatively stable. Often times I don’t use any black, simply because a single layer of clear will give me a dark enough surface for my needs.

One of the first questions on perusing my list you’ll ask is “what is the difference between Low and  Medium firing enamels?” I didn’t know, so I bought both and tested. (Doing some reading probably would have been less time consuming. Thompson sells their Thompson Enamel Workbook for around ten bucks) The answer is the amount of expansion. The Low expands minimally, and it goes up from there. When they say on the website that layering different expansion levels ‘will produce crackle effects’ they are right! When that happens in your experimentation, you’ll know what they mean. I’m still not completely in control of what happens as I’m still learning, so all I can say is ‘keep experimenting’, but from memory, if you fire a thicker transparent low expansion layer first then add a thinner white low expansion layer you will get the white (the upper layer) cracking and peeling on firing. That is in my experience, anyway. I’ve found low then medium to work ok, but it’s been a while so I may have it confused. Sorry! I’m only an enthusiastic amateur!

Thompson
BC-1070 Medium fusing white
BC-969A Low fusing clear transparent
BC-303L Medium fusing clear transparent

533 White
772 Black
930 Chinese Red

Recent Additions: November 2013
936 Beige We had great fun with this colour in September at Danaca Design during the workshop I taught.

January 2015
GC-16 Cobalt Blue I finally used the ground coat in anger and whaddya know, it works a treat!  My tip is to fire a BC layer – (BC = Base Coat) of clear – medium or low, depending on the application or the Cobalt Blue Ground Coat if you’re using lower quality steels (read ‘tin-can’ steel – it’s really appalling for anything other than samples, but soooo cheap!) Nothing else will stick on first go. Other steels are less finicky (so a colour straight on is just fine), but if you’re going to build up the layers and don’t want to risk crummy adhesion, definitely go the GC-16 as the starter. It has reasonable adhesion to the 3″ x 3″ low-carbon sample squares that Thompson sells, which aren’t sandblasted but have a subtle imprinted randomised pattern. Though as you might guess, better adhesion to a sandblasted surface.

Christmas Ornament made from welded tin-can mild steel and vitreous enamel. The grey is Thompson GC-16 Cobalt Blue, while the white is a medium fusing white, over a layer of the ground coat as a base
Christmas Ornament made from welded tin-can mild steel and vitreous enamel. The grey is Thompson GC-16 Cobalt Blue, while the white is a medium fusing white, over a layer of the ground coat as a base

I’ve also recently purchased the Thompson Enamel Workbook and a sheet of the solid colour decal material (I have some decals kicking about that I made in Bristol but these are mostly text) so I look forward to testing this for a new way of working with decals.

WG ball
Light Blue 6117
Metallic Light Silver
Sheet Steel Groundcoat
Ivory
Sky Blue
Royal Blue
Dark Green
Yellow
Clear Flux
Metallic Dark Silver
Metallic Gold

I’m yet to try a lot of the WG Ball versions (busy year…) but the ones I have used have seemed a little more grainy. It is possibly my mixes haven’t been great, as at the time I didn’t want to put the whole bag in solution so I only used a small portion of the whole amount.

firing
ENAMEL: Make sure your enamel is thoroughly dry before putting it into the kiln. Sit it on or near the kiln if you want it to dry quickly, or use a hair dryer or heat lamp. It must be dry before firing or the water will steam and take some enamel with it, leaving marks and adhesion issues in its wake.

KILN: Arrrgh! I cant answer this one! Firing depends on a lot of factors, your kiln, your material and the enamel. Some enamels say don’t fire over 800°C [1470°F] while some (W.G. Ball) say fire between 800-820°C [1470-1510°F]. Sometimes you need a minute, sometimes 2, sometimes less if your kiln responds well to the door being open, or more if it’s a little slower on the heat or it’s a big piece of steel.

Generally enamels are best fired between 750-800°C [1380-1470°F] but I have a note here from a workshop with Elizabeth that reads “don’t fire steel over 800°C – it warps” right after a note that says “Steel: in industry grip coat fired @ 840°C [1545°F], enamels @ 800°C.”

My advice? Test, sample, try out, evaluate, trial, check and study. It will always depend on your kiln. I typically wait for the kiln to get back up to the start temperature before opening the door, but sometimes even this is a little short. The opposite side is that if you’re using a delicate enamel (painting/screen printing enamel) you need to be more gentle.

 

surface
As mentioned earlier, on the Thompson website you can also find pre-enamelled steel squares, which are great to practice on. They have a base coat so just about anything will stick to it. In the workshop I did with Elizabeth we were encouraged to use enamel as glue, and put all sorts of sands and even metal shavings into the wet enamel so it would fire solid. That’s where I got the idea of using my sandblast grit as a surface texture.

Like any other sand, fire scale or shaved metal that you want to use, glass beads go onto a layer of fired enamel, and then are fired to get them to stick. It’s up to you if you add layers over the top – such as clear – for binding, but I generally don’t. That way you can really feel the texture (though you have to be prepared to lose some if it’s a really fine sand). You can use a product like Klyr-Fire to help with adhesion until you fire the work, or lay down some marker or a stamp on which to sift your sand/grit/favourite-jewellers-enamel and then shake of the excess. Or you can use unfired wet process enamel to bond it – just add the grit once you’ve put down your layer of enamel, then wait for it to dry before firing.  Now, in the case of glass beads, the more you fire them, the less ‘beady’ they become so if you’re using larger glass beads it might be the very last thing you do if you really want them to stand out. Peter Daglish in the studio in Bristol was using big Murano glass roundels as eyes for his works. The finished result bulged off the panel which was kinda freaky!

using graphite
Graphite (in liquid or pencil form) needs to be applied onto a base of fired enamel. The layer of graphite then must be fired to get some of the graphite to stick. To finish, cover with a layer of clear enamel, and of course, re-fire. If you use pencil some of the graphite can rub off, so you may what to try to shake it or use a clean brush to coax it off (after firing) before you apply the clear, as the linework will smudge if there is remaining graphite on it. Sometimes it’s not as noticeable as others. An example is here,

not my magnum opus… but kinda cute. shoulda cleaned off the edges a little more

If you are so inclined to draw with graphite pencil on your piece, you might want to get a drawing surface by mixing some clear enamel with porcelain slip and then firing a thin layer of the mix onto your piece. The ‘tooth’ of the slip helps you lay down a lot of graphite. Porcelain slip is available at any ceramics/pottery supplier. In Melbourne I can direct you to Northcote Pottery Supplies, but I don’t know who you would go to anyplace else, sorry! It’s pretty common, though usually sold in large quantities. I managed to get some from a friend, which, once rehydrated, even managed to survive the trip to the ‘States.

*new graphite experiment results*
So I have been at it again, firing some graphite directly over a clear and a half clear/half red enamel surface. The pieces below were created by firing a couple of very thin layers of enamel (Thompsons Clear and their Chinese Red that was a half/half mixture with clear, a mixture I created to help the red stick first time around or to provide a bit of colour to an undercoat for the red) and then abrading them back with my trusty set of 3M diamond hand pads. On the freshly abraded surface I was able to draw directly with graphite pencil and then fire, and this was enough to get the graphite to stick beautifully. On the broch – the piece in the centre – I added an extra layer of clear over the fired pencil, so with the grey on grey the linework doesn’t come up in the photograph too well, though that is not all in the photography, as in fact in some lighting it’s hard to see with the reflections on the layer of enamel.

d Melissa Cameron_Enamelled Trio_2013

However the Cardinal Point ring on the left-hand-side also has two layers of graphite on different layers of enamel, so you can see the shadowy layer on the top-left of the drawing that is the layer under the final layer of enamel. The Locations ring on the right only has one layer of graphite, which sits atop the second (and final) layer of enamel.

d Melissa Cameron_Pin-swap brooch_2013

A slightly better view of the linework…

more
If you need more help there’s W.G. Ball‘s instructions on their site, and of course there are always books. I believe that Elizabeth had some input into The Art of Enameling by Linda Darty. This is available on your favourite online reseller, as well as at the Thompson website, where you can also get your copy of the Thompson Enamel Workbook of course!

*NEW*
for some tips on how Thompson enamels behave, check out this on the Schlaifer’s Enameling Supplies site

enamel brands: behaviour of unfired and fired enamels
I’ve recently been working with my WG Ball enamels in earnest, enamelling a series of neckpieces that I have also enamelled in a Thompson colour, a 930 Chinese Red. The WG Ball colour I will use for comparison is their 10104 Sky Blue. Both are liquid enamels that I bought in powdered form, and both applied over a Thompson Clear (low fusing) base. First up, I have found the WG ball enamels to be grainier than the Thompson ones when in solution, and the application to be tougher as they either don’t give good, even coverage (too little water) or when they are covered nicely they then ages to dry and have a tendency to run as they dry (too much water). I’m yet to find a good medium, though as I’m newer to them than the Thompson ones it might just be my water adding and mixing technique. I’ve also tried grinding them down more to help them mix and therefore have better application results, which worked but due to other issues (see below) seemed to be of minimal overall benefit.

The other issue is that thus far, the aforementioned Sky Blue, (as well as some of the other WG Ball enamels I have tried) don’t seem to take on a glossy surface when fired. Again, this is measured in comparison to the Thompson colours (and other colours from Elizabeth Turrell’s studio – I remember a German range there) that I have worked with.

Even to get a semi-gloss is tough. It could be that in my temperature control and timing I am missing the optimum fuse point repeatedly (but once again, I’m hitting the desired time/heat fine with other brands), so the best I can say is that it is very elusive. I’ve either managed to overcook them (they started to flake off the work) or have them look slightly under-fired, with the tell-tale lack of glossy final surface. In the end I have resorted to adding a final layer of clear.

To save time I decided to try mixing them in with some Thompson low-fusing clear. This turned out quite well, to the point that I have begun to mix some of my own colours, thus far just sticking with a single coloured enamel with a single clear.

This works especially well if you are after a more transparent finish, which is something that I happened to want at the time, but in the long run is not really a solution to the gloss-less problem. So far the combinations have played well together in mixing, (meaning they actually go onto the work better) and in finish, as they have fired easily to the desired surface finish.

In my work I have been trying to dilute the strength of the colours a bit too – I’m not into opaque colours at the moment (I like the black of the steel to make itself known and the variegation of the thicknesses of the enamel over a surface give what I find is a desirable smokey quality), but opaque colours are just about everything that I have. In my experiments I’ve been making a mixture of 2:1 (the ratio being premixed clear to premixed coloured enamel, or even more on the clear side of the equation for stronger pigments or to get lighter colouration) on some to ‘water’ them down a bit. That seems to have worked well.

*update #1

I have finally applied some of my collected rust to some white enamel. The substrate is from a can (Ok, you got me, it was a can that held a whiskey bottle…) that I sandblasted, so the metal is not perfectly flat.

Rust on enamel on steel. Test sample on steel can, Melissa Cameron, 2013.
Rust on enamel on steel. Test sample on steel can, Melissa Cameron, 2013.

As you can see there are two sets of markings visible on the piece that are a result of the process. There is the maroon-brown tiny specs that have good coverage and then there are some black larger pieces, which I think are actually interference. The way I collected the rust was to rub some quite fine-mesh steel wool over a rusted piece of steel, capturing it in the little bag you can see in the image. I have a feeling that the black marks also on the surface are actually smallish sections of burned steel wool. On the piece these black particles have more texture than the red coloured section of the ‘real’ rust, which adds fuel to my idea that they’re larger steel particles, which brought with them more substance than the actual rust dust.

When I applied the rust dust it was really fine and powdery, so it settled in clumps on the surface of the enamel. Worried that I wasn’t getting much coverage (and I would lose that which was only sitting on the surface and not actually in the enamel) I then stirred it into the still-wet enamel fairly thoroughly. I remember thinking at the time that I should have stopped combining earlier, as there were some nice track marks of clean enamel through the rust surface earlier in the process, which got lost as I kept combining the two. Still, that’s something to work on for next time.

Also, having had a go at an old-fashioned dip-pen on enamel thanks to Nancy Bonnema at my recent enamel class, I’m now wondering if the super-fine rust dust would mix into a pigment to be drawn with easily.

*update #2

For some handy PDF’s on enamelling concepts and suitable metals (in Europe the first one and in Australia the second) check out Arcelor Mittal’s Steel for Enamelling and Enamelled Steel User Manual for enamelling process and a bit of the chemistry involved, and if you’re an Aussie and are interested in what BlueScope Steel calls their low carbon steel range have a look at their TECHNICAL BULLETIN TB-25. (Hint, their cold-rolled low carbon products go under the names CV2S1 and CV4S2.)

73 thoughts on “Enamel on Steel – some insights”

  1. Hi,

    thank you for this blog! Very interesting!

    Just a question I hope you can answer: are Thompson lead free enamels and leadfree WG Ball enamels compatible with one another???

    Thank you for answering!

    Best, Katinka

  2. Hi Katinka,

    I’ve not had any problems using the two version of liquid enamels together; in fact I’ve been known to mix them up to make semi-translucent versions of WG Ball colours using Thompson LF clear as the base. Let me know how you go.

    Melissa

  3. Hi Lynda,

    A: a lot of places. For fresh mild steel sheet that I can cut with my saw, I got to Online Metals, and get regular mild steel, or even better, low carbon mild steel. I use recycled material a lot, and I find that in the recycling, or even on the street. Literally! And when I’m using a laser cutter I use what they provide, or specify low carbon steel when I have the chance – so when I use Pololu to cut, I go wither their list of steels, and when I use Laser Services USA, I specify the steel, and pay the extra to get what I want.

    Hope this helps!!
    xx m

  4. Hi melissa, thanks for your response. I was enlightened and I think I am more interested about how camping mugs made. May I ask what kind of enamel, or specific enamel to be used for in coating stainless mugs that would be safe for food and to avoid as well mistakes upon ordering it internationally. I’m afraid might order a wrong one. I have actually watched some videos how camping mugs made, one of the videos I have watched was with Emalcoware (company that makes camping mugs based in UK) but its not indicated what kind of enamel they used. Hope you could help me. Thanks! Will wait for response. 🙂

  5. Hello!

    How well have the normal enamels from Thompson worked on stainless steel for you? Hoping to do some enameling on stainless, and I have plenty of enamel that I use for copper. Will it work?

  6. Hi Melissa, still having trouble locating low carbon steel for jewelry making. Went to onlinemetals.com, but the thinnest sheet they seem to have in 16 gauge. Can you possibly provide a link to the sheet you use? That would be great!!!
    Thanks! Jo

  7. Hi Christle,
    Since I make jewellery and art objects I don’t actually have any idea which is and which is not food safe enamel, I’m sorry to say. The time I worked with pre-enamelled mugs I know that the steel was magnetic underneath, so it wasn’t stainless steel, and when finished the mugs were offered as art pieces, not kitchenware, so they were not expected to be used. I have seen people fire Thompson white liquid enamel (I don’t know which one exactly, but I’m tempted to say Thompson BC-1070 so that might have been it – it was in a workshop I did) on the outside of a camping mug, which remained food safe as the new enamel was unlikely to come into contact with food. You will need to be in contact with the enamel manufacturers to find out if they guarantee their enamels to be food safe, as this is information that I just don’t have.
    Good luck in your search, and please consider sharing the info that you may find.
    Melissa

  8. Hi Kim,
    I find normal enamels work fine on steel over a layer of liquid enamel, but they are too coarse as the first layer, between the steel and subsequent layers of enamel. They don’t key into the sandblasted surface well at all, and so tend to ping off as soon as you pull them from the kiln, and continue to ping as they cool. They do work great once you have a good layer (by ‘good’, I mean one that has no breaks in the layer or pinhole blemishes to the surface) and fire well onto a liquid enamel base. I’d suggest a ground coat or base coat from Thompson (search: liquid enamel base coat) as the first layer onto the steel, and then you can fire away with all of your existing enamels.
    Good luck!
    Melissa

  9. Hi Jo,
    Confession time – I have not directly bought any low carbon steel sheet, ever! However, I do (now) specify that I receive my laser cuts in low carbon steel (304L or 316L) and so my laser cutter has included with the shipping documentation the invoice for the payment of the low carbon steel, for proof that the steel I have received is as ordered. So, I’ve hunted down my paper trail, and found the company from which Laser Services USA has just this year used to purchase me some low carbon sheet. It is a company called Slice of Stainless. For lasercut jewellery works thus far I have used regular stainless and had no issues with rust, except where I have introduced other steel (in which case I wanted to promote the (dis)colouration it brought forth). The low carbon was ordered for my HEAT works over the last year or so, as I was worried about enamel adhesion with such large enamel sections. I’m fairly sure that Beate Gegenwart uses straight stainless steel in all her works which are often half polished steel and half enamelled, and seems to have no dramas. Except for firescale removal – something I tend to use the sandblaster to deal with, if I bother 😉
    Cheers
    Melissa

  10. Hi Melissa, I’m beginning to investigate enameling on thin pre-enameled steel sheet, and while perusing your blog I saw the questions about mild steel. I recommend McMaster-Carr –mcmaster.com–as a source in the US. Simon Cottrell sourced his steel there during a workshop a few years ago and I’ve been ordering from them ever since. Hope this helps some of your readers. Meanwhile, if you have any tips about fabricating with the pre-enameled sheet, I’m all ears. Cheers, Marjorie

  11. Hi Marjorie,
    Thank you for sharing that one – I get my flux and a few other things from McMaster-Carr, but for some reason the obvious never occurred to me! Leave it to Simon to teach us all…
    As for pre-enamelled (whiteboard sheet, yes?) I’ve not done a lot of it myself, but I have seen it (carefully) scored and bent at a very small scale – mostly by Kaori Juzu – and I’ve been told that a sturdy blade (not even diamond – perhaps 2/0?) and a good amount of grease (Burr life or some such) gets through it no problems. I’ve put it to a few guillotines around town and had no problems, after taping of course.
    Aside from the second-hand knowledge, I’m not much use, I’m afraid. Maybe someone here will have more hints..?
    xx
    Melissa

  12. Hi Melissa

    I’d like to clear up some misconceptions that you or your readers might have about carbon and steel. Carbon is an essential alloying element in steel, without carbon, steel is iron. The carbon is quite solidly bound into the crystal structure of steel but it is possible that there is a small amount of off gassing when the steel is above its transion temperature.

    The actual amount of carbon in all steels is very low. 1 per cent carbon is quite a lot, above about 2 per cent it starts to become cast iron. Mild steel, which is the most commonly encountered type, is another name for low carbon steel has on the order of 0.05 – 0.25 per cent carbon, usually on the low end of that range.

    Higher levels of carbon are usually desireable in steels as carbon is the primary way traditional steel gains strength, hardness and toughness. As a result high carbon steel is always more expensive than low carbon and often has more exotic alloying elements in it to specialise its mechanical properties.

    Stainless steel has a lot of other alloying elements, notably chromium. In stainless it is much more common to describe alloys in terms of whether they are low or high carbon. The non-magnetic varieties such as 304L do often have low carbon content but it is the very high chromium and nickel content which make them non-magnetic. 304L is low carbon like mild steel (0.03 per cent), but has 18 per cent chromium and 8 per cent nickel. 304L is also known as 18/8 and is pretty much the most common stainless there is. Chromium also improves the hardenability of steel so low carbon stainless is even more common than low carbon traditional steel. If you encounter anything other than a knife blade marked “Stainless” without other details it is usually 304 or a similar grade.

    So if you would like your stainless to rust a little, get low chromium grades. If you pick a random piece of cheap stainless or mild steel it is very likely to be low carbon, especially if it is thin. Whether a piece of steel is magnetic or not tells you nothing about its carbon content.

    I am not certain that carbon off-gassing would be significant enough to cause bubbling issues anyway, possibly it is one of the other alloy elements in high carbon steels, but if it is, low carbon is not usually a problem to find.

    I hope this has been informative.

  13. I just found your websight, and I need your advice or insight, in the 1970’s I was using Thompson enamels they were in Chicago at the time. I designed a clock each numeral was on a three inch diameter textured silvered steel round. Now many years later the disks are flaking off because of earthquakes in California. I need to either repair or discard many of the disks. I live in Los Angeles, am 84 years of age. Should I just ignore or attempt to repair, I would need to find a source for the disks and try to start from scratch or just put a surface coat or clear glue to prevent further damage . Any advice would helpful. I can email photos of the disks to you.

  14. Hi Toby,
    Your query sounds a little above my experience so my suggestion is to get in contact with Thompson Enamel directly. On their FAQ page they list their contact email and telephone: “You can find a variety of tips on our “HELP” page. Our technician is also available by phone at 859-291-3800 during business hours; Monday – Friday 8:00 AM – 4:30 PM Eastern Standard Time. The technician can also be reached via email at techsupport@thompsonenamel.com.”
    I’m sorry to have to pass the buck on this one but I’m not able to advise on enamel, or even metal, conservation. Should you choose to re-do, Thompson are also the best source for the type of 3″ circles you might need.
    Good luck in your search,
    Melissa

  15. Thank you for your extensive documentation and work collecting enamel-on-steel information! I found your blog with a search of “enamel on steel”, because I was given an old Renior/Matisse (commercially produced) bracelet that had badly damaged enamel insets. I removed them expecting copper, but found them to be roller formed steel (approx 24 gauge, with a randomized, roughly pebbled texture). Since these panels were created in the 50s or 60s I am assuming they were produced with leaded enamels, and that the rough pebbled surface was a means to mechanically adhere the flux layer to the steel.

    Thank you for the firing information, I will commence repairs with medium firing white, in an effort to get a good stable ground. Also, I have seen bead makers use heated vermiculite (in a crock pot) to anneal the finished enamel. Do you have an opinion on the probable efficacy of this step? I’m of the “can’t hurt” mindset. 🙂

  16. Hi Jean,
    Thanks for stopping by. It sounds as though there is a similar surface on Thompson Enameling Iron squares, as in my experience the finish on those also looks pebbled. In the case of your piece it has obviously held before, though (again, only in my experience) it’s not the greatest foundation, at least, not as good as a sandblasted surface. That said, my money is on you as you sound well prepared.
    I have to say, you lost me at vermiculite, as I don’t hang with many bead makers these days. From my paltry amount of research I will agree that it won’t hurt, but the reason that it is done in beading is to mitigate the effects of cooling too quickly – and especially the consequences of a huge temperature differential between the interior and exterior of the glass.
    With glass on metal you introduce a few different factors that change the equation significantly – an attached heat sink/pad that cools slower than the glass does, and a much thinner glass layer. I don’t think it would harm the enamel, but I have found no reason for there to be much benefit to it either.
    When bringing larger enamelled pieces out of the kiln it is common to apply pressure – in the form of large and heavy iron/steel weights – to a work (copper or steel) to help flatten out the underlying metal while it is still at high temperature. This is almost the opposite handling instruction of putting in vermiculite, and while I won’t go so far as to say it’s helpful in adhesion (though it does help the cooling process, for whatever that’s worth) it’s a (sometimes) necessary evil in working with metal and glass when hoping for the result of a relatively flat enamelled sheet. So while I don’t go around trying to scuff up my enamel, I know that it is fairly resistant to some wear and tear, and have not had any reason to try and slowly and steadily cool down the glass when working with it on metal.
    But owing to the fact that I had to google vermiculite, I’d say that you should probably find a more reliable source!
    Hope it all works out well, I’d love to see pictures.

    Melissa

  17. I am relatively new to enameling and and have some tins that I want to try and enamel the lids. I successfully torch fired one but tried kiln firing one with liquid enamel – it set allight in the kiln!!! Any ideas as to how I can achieve a consisent result with torch firing?

  18. Hi Jo,

    I’m not sure if you saw the previous page of comments on this post, but I do have a brief description of how to make the most of torch firing (I’m going to add that in below*). A good place to check is the Ganoksin archive, on which I’ve just found a lengthy post about the process. Another place that might be useful in checking out is Grains of Glass, a private network of enamel artists. They have loads of post and bit and pieces, thought you will have to become a member (free, I believe) to check most of it out.
    I have to add that I am worried that you set fire to a piece in the kiln; it makes me think there was some sort of flammable coating on the metal, that the metal was not steel or copper or silver or gold, or that the kiln was at a really high temperature. Any of these three scenarios are not ideal for enamel adhesion, in fact I put the long term adhesion potential at very low. Anyway, Hope some if this is useful, and please stay safe and good luck!

    *From the a previous answer:
    My experience with torch firing was rather rudimentary but thanks to the delightful and insightful Kat Cole here are some tips for torch firing onto steel:
    “- Kiln firing limits the amount of warping that happens because the entire piece is heated evenly, which is possible with a small piece and large torch.
    – That being said, I have been able to fire a 10″x16″ 20 gauge (25.4cm x 40.64cm x 0.812mm) sheet of steel with liquid enamel with a large torch tip (but really not that big compared with the size of the sheet) on an acetylene tank.
    – Because steel does not spread heat around as evenly as copper would, you can actually get quite a nice range of firings across one piece of metal.
    – But because of the warping I have not been able to torch fire a second time without quite a bit of enamel cracking off.
    – The thicker the metal the less it will warp and I have had success torch firing smaller pieces of thicker steel multiple times. ”

    So, based on that description, ideally one would attempt to fire from the rear of the piece. I would suggest (beyond the usual – sandblast well, make sure the enamel dries fully before you try firing, you may have to forgo a ground coat/layer of clear first as you’re likely facing a one-fire situation) use as large a torch as you can find, get behind the work (propped up or lying on a steel mesh on a tripod with the flame coming from under) and be prepared to stand there for a while, so wear proper protective gear – leather gloves, mask, goggles/green glasses etc. Try and keep the heat even and moving, and if the piece is larger maybe expect to move across from one side of it to the other, hoping that as the piece you have already set is cooling it does not crack in the zone between the molten and the already-cooled.

  19. Hey Shanhong,

    As I mention in the article, I know that Koodak in Melbourne stocks some Thompson powders in Australia. WG Ball and Thompson also both ship to Aus- feel free to check the links in the page for details.

    Cheers
    Melissa

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