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Cast Iron Vitreous Enamel Process?

Luke Rickert

Luke Rickert

Hot Rolled
Joined
Oct 24, 2007
Location
OSLO
I have searching online for information about the process of applying vitreous enamel to cast iron parts. I can find information on jewelry but nothing on what is really a very common industrial process (or at least a historically common process) Maybe I am using the wrong terms but hopefully someone here has some ideas.

My only even remotely related experience is with ceramics in school many years ago. Without having the necessary equipment on hand I can't experiment but given glazes for ceramics are relatively simple, can you apply enamel coatings to cast iron with the same sorts of basic equipment (water suspended glaze and a kiln etc)? It seems likely it is more difficult with iron as getting the coating to stick might be hard as partially fired ceramics are rather more open grain than cast iron and oil etc is going to be much more of a problem with iron. I would guess you also need to use solvent based glaze as the water based might cause rust. I imagine the temperatures are going to be lower as I think the iron would melt with high fire glaze temperatures.

Maybe I should just be looking at powder coatings but they are plastic and there is something nice about real enamel.

thanks

Luke
 
Are you interested in replicating the enamel similar to a Le Creuset dutch oven?
Wonder if there are videos of the process on-line?
 
More or less like Le Creuset, old school European workshop equipment more precisely. I can't think of a modern example of a tool with an enamel coating so I am guessing it is either very expensive or very difficult for some reason. I think it is still commonly used on sheet metal for appliances and that sort of thing although perhaps they have gone with paint/powder coat and cheaper stainless for washer baskets and that sort of thing.

Luke
 
whidbey said:
I have searching online for information about the process of applying vitreous enamel to cast iron parts. I can find information on jewelry but nothing on what is really a very common industrial process (or at least a historically common process) Maybe I am using the wrong terms but hopefully someone here has some ideas.

My only even remotely related experience is with ceramics in school many years ago. Without having the necessary equipment on hand I can't experiment but given glazes for ceramics are relatively simple, can you apply enamel coatings to cast iron with the same sorts of basic equipment (water suspended glaze and a kiln etc)? It seems likely it is more difficult with iron as getting the coating to stick might be hard as partially fired ceramics are rather more open grain than cast iron and oil etc is going to be much more of a problem with iron. I would guess you also need to use solvent based glaze as the water based might cause rust. I imagine the temperatures are going to be lower as I think the iron would melt with high fire glaze temperatures.

Maybe I should just be looking at powder coatings but they are plastic and there is something nice about real enamel.

thanks

Luke
Click to expand...
there still are countless objects made from cast iron and enamel.
pots and pans, grates on stoves to name a few.
i wonder if there are still cast iron bath tubs being made.
 
the sign in cranium's profile picture is also probably enamel but smooth sheets might be easier than castings which probably require a bunch of prep and very smooth surface finish as you can't use "body" fillers if it is going into an oven. Still I haven't see anyone selling iron enamel powder or anything like that.

L
 
There are a few places in the US that can do this, and should be some in France. China has a bunch.

To find out more, search "porcelain bathtub repair". Or ask the guy in Seattle who makes little wood stoves for boats - the "Sardine" who he uses.
 
We had a cast iron bath tub re-enameled a few years ago. We ended up sending it up to Lancashire in the end but I do remember there were companies on the South coast (UK).

My understanding of the process is that the item to be enamelled is heated in a furnace to red heat and then the enamel powder is sprayed with a gun not unlike a large powder coating gun onto the red hot surface where it melts and fuses.

I suspect your limiting factor is going to be the ability to heat a large cast iron object to red heat and maintain that heat while you're spraying on the enamel powder.
 
there is virtually none of this being done in the USA. That place in Missouri might be the last one.
A few large companies, like Kohler, still do vitreous enamel on the very high end of their bathtubs and sinks- the infrastructure required is expensive and large scale.

There used to be smaller shops in many US cities that would do sheet metal signage this way- much smaller ovens are required to do 16 gage, rather than 400lb iron tubs. But silk screen, then vinyl signage cutting machines killed that industry 40 years ago, at least.
There was ONE shop left in Washington State doing this in the 70s, it was already obsolete tech then, and he mostly was working with artists even then.

The cowboy coffee cup style enamel plates havent been made in the USA for decades now- the closest is one huge factory in Mexico, but most comes from eastern europe now.

It is not financially feasible to do this in the USA on a job shop basis, and nobody does. You can buy a $10,000 stove from france that had this done in house, but thats about it.
 
One of the issues with enamelling was some enamel frits had a high lead oxide content to lower the melting point. A lot of the cheap import enamel plates,cups and bowls still do.
 
I saw a episode of this old house, or similar, Norm went to the tub factory. Tub was heated to red heat and then he shook a sieve of powder all over to coat it. Tub was on some kind of spinner. then it had to be slowly cooled so nothing cracked. I have seen cast iron and stamped tubs for sale. I assume enamel coated.
But they call some paint enamel?
Bil lD.
 
Thanks for the suggestions and info. By searching for enamel "frit" I am finding much more online. I found a company in Germany that sells the materials (Enamel >> Wendel-Email) so they might be worth talking to. In Europe anyway it looks like there are still some companies that I could send parts to (thanks janvanruth). The parts I am thinking about are quite small and will need to be heat treated (stress relieved) so I will be getting an oven capable of more than the 800C required for enamel so if I can get the frit it might be worth some experiments.

The demise of American porcelain enamel is interesting, it seems like a useful process but there are so many modern coating options that are easier to apply. I would guess that most of the american enamel shops probably didn't survive the switch from lead based frits as that would have come around the same time as the general decline/consolidation of american industrial manufacturing.

I also found this, they use electrostatic application (like powder coating) Porcelain Enamel Powders

Luke
 
EmanuelGoldstein said:
Remember when you got new plates every year, instead of a sticker ? Keep them cons busy :)
Click to expand...

I have lived in either Washington or California, and owned cars since about 1973, and never got new plates every year. In Washington, they used to send you new plates every 7 years, but they stopped doing that in 2014, and now, unless you lose em, you keep the same plates for a long long time.
 
Ries said:
I have lived in either Washington or California, and owned cars since about 1973, and never got new plates every year.
Click to expand...
I was too young to drive so just got to open the plain brown wrappers they came in ... the year was stamped on the plate itself, no sticker. And I think they came all at the same time instead of staggered, but that could be a memory failure.

Whippersnapper :)
 
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