Enameling onto steel appears to be a sensible idea based on the fact that antique enamel signs were on steel. How hard can it be?
The first task was to make a mask. I did this using the Sainsmart Genmitsu 3018-pro.
This was designed using Carbide 3D and machined using a 1.2mm diameter slot drill.
The centre of the g, e and o were all located using thin copper wire. The wire being superglued across the MDF mask.
The plan was to base enamel the steel plate. Then once it had cooled down, place the mask onto the enamel and sieve a fine dusting of a contrast enamel on top.
I removed the finished part from the Prometheus kiln (set at 810°C for enameling) and let it cool. The enameling appeared to have worked really well. However, as the part cooled to room temperature I heard a “ping”. Then another “ping”. The enamel was cracking and coming away from the steel. I ended up with a number of pieces of glass.
The glass was obviously shrinking at a different rate to the steel and delaminating.
Another trial, this time using WG Ball 477 clear flux as a base coat. I sieved the enamel powder over the mild steel.
Note that this is after abrasively cleaning and pickling the steel sheet.
I then fired this flux coat at 810°C.
The results were rather good. The enamel was intact after cooling and the lettering looked good.
The upper sign was left in the kiln longer and as you can see the lettering has started to blur. With the lower sign I watched as the enamel powder melted and removed it from the kiln before it started to flow into the based coat.
At this point I thought I had solved the enameling onto steel challenge.
Failure
The failure wasn’t as severe as the first trial without flux. However, after approximately 12 hours some of the pieces showed signs of cracking on the edges.
The old antique signs were very robust, lasting outside in all weather conditions for years.
It appears that I need to use a grip coat enamel that has metal oxides in it and so designed to adhere to steel. Also I need to sandblast or to give the steel a rough surface that the enamel can lock onto.