Guys,
If polyspan is applied with Nitrate dope then finished with Butyrate (Sig, Brodak's) does the Butyrate melt in the top layer of the nitrate like it does to other Butyrate coats or just glue itself on top of it?
Seems if it just glues on top any break in the surface could cause the two separate.
Can you use all Butyrate to adhere the polyspan?
Best, DennisT
Hi Dennis,
Butyrate will adhere extremely well to nitrate as the solvents in butyrate soften the nitrate and blend the nitrate/butyrate interface. Nitrate is extremely flammable and was used in the very early days of fabric covering on airplanes, in fact nitrate in the twenties and thirties was available in colors as butyrate was just being introduced.
Butyrate was developed due to the extreme flammability of nitrate - butyrate, while it will burn & sustain combustion is much less explosively flammable than nitrate. I have peeled a sheet of the nitrate dope off of a test piece, put it in a metal pan on the floor in the middle of my hangar and put a flame to it. A foot square piece of nitrate was completely gone in less than a second.
Also, butyrate has more than enough adhesion to use when applying polyspan, silk, or silkspan.