Hey all!
I’ve been fixing 100 yr old sewing machines during my covid quarantine. Some of the cast iron treadle bases need to be recoated. I’m considering powder coat, but also thinking about going back with the historical finish.
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The historical Japanese Style Lacquer (Jappaning) Calls for 2 parts linseed oil, 5 parts turpentine, and 3 parts asphaltum to be baked at 200c for 2 hrs.
I have a couple of concerns about it- outgassing, size of the pieces etc.
Does the metal shop posses an oven big enough for one of the treadle legs? 24x18x1.
I can’t imagine baking asphaltum and turpentine is going to be great to breathe. If there is an oven- would these materials damage it, and is the oven well ventilated enough?
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I will be taking the hot process saftey classes etc. after I’m vaccinated, this is just fact-finding.
The Hand Tool Rescue YouTube channel did an in-depth Japanning comparison a while back. He compared four recipes as well as spray paint and clearcoat.
Very informative. I found the link for you.
He does mention that recipes with asphaultum smelled horrible while baking, with a non-trivial baking time.
He also has a disciplined, multi-step heating approach to avoid wrinkling and takes it up to 400F (similar to your 200C) for a hard finish.
The two cold-cure (no bake) recipes he tried did not pan out - too grainy.
According to him, a reasonable (and much easier) approximation is to use a low gloss enamel spray paint with an amber shellac topcoat to add a hint of brown similar to the original.
If you don’t want to watch the whole 40+ minute video, the summary of the winning approaches start about 37:50 into the video, but watching the whole thing is worthwhile l, IMHO.