What I plan to do differently next time is 1) thin the paint considerably with something very volatile, probably acetone 2) wait as long as possible between application and baking, this would probably become less necessary the thinner the paint is, and 3) do the baking in steps, probably something like just bringing the BBQ to 300 degrees then shutting off until cool, then up to 400 degrees and then cool, and then finally bringing it up to 400 degrees again and holding that temp for an hour. That might also become less necessary if a thinner coat is used.
My first go around with barbecuing a gisonite/linseed oil mixture on my Prentiss base cured very well. The second attempt on my static jaw did not cure as hard and almost stayed sticky. It think a thicker coat was a contributing factor to the problems on the static.
I also wanted to copy this content from page 1144 of the Vises thread over here because there is some good info on the Ford F-102 spec and the details of what went into Broncs japanning.
Originally Posted by 91bronc300
The same as you. Gilsonite and linseed oil and solvent. I'm using a mix of D-limonene and naphtha for solvent and boiling lead oxide as a dryer into raw linseed oil. I'm guessing your results are in the thread drivesitfar referred me to?
Edit: I found it on page 17. So you baked immediately after painting it on? My thinking was to wait a few days to let the linseed oil polymerize before the heat but you are getting a nice hard coating with baking immediately apparently. The finish of your swivel base is more matte than mine, I wonder if that is more because of the immediate baking or something with the mix.
Originally Posted by McBrownie:
That could very well be. Yours is much glossier. I started with the F-102 spec as described in here:
http://www.mtfca.com/encyclo/P-R.htm
I was going for a coating that was period correct for the vise. On second look, I didn't add a thinner as listed in the spec! Don't know how i missed that and I'm going to try that next. Can you explain what "boiling lead oxide" is? They seem to refer to something like that in the above link.
Originally Posted by 91bronc300
I think one of my issues is that I made my solvent too heavy with the D-limonene (syrupy) and too light with the naphtha (more volatile) so it doesn't thicken up much or quickly once applied. Although I did cook the paint itself down to a pretty thick consistency.
For the linseed oil I used Sunnyside raw linseed oil and then measured 1 part to 20 by weight of lead oxide AKA litharge and then boiled the linseed oil until most of the lead was taken up by the oil. From what I have read (which was scant) boiling linseed oil should be a long process, approaching a day in length, but I only boiled mine for about an hour. I did two batches of oil both being about 2 lbs of oil by weight. 1 part to 20 by weight is about 45 grams of litharge to 2 lbs of oil. The first time I tried keeping the oil under a low heat and deep vacuum in a vacuum chamber for days but this seemed to be a waste of time, so for the second batch I just boiled it openly for an hour and stirring occasionally (holding my breath near the pot!).
There was also a second difference between these batches, the first batch of oil was 'washed' with salt water and sand to remove mucilage and phospholipids before cooking in the litharge. With the second batch, the non-vacuum batch, I did not wash the oil with salt water and sand.
So far I have only used the Japan black that came from the first batch of oil.
