This is a follow-up on the original question of putting clear dope over water based stain. I expanded the test to include some “dope over” combos we might encounter in trimming techniques, repairs, or new planes with film wings and doped / covered fuselages.
I was also interested in using the “Windex method” of adding film trim (numbers, designs, . . .) except over doped surfaces prior applying a clear dope finish coat over the entire plane. (obviously can’t use trim solvent!). After some thought, the test was expanded to add the following:
Monokote (True Red) – (Coded “M”)
Ultrakote (Bright Yellow) – (Coded “U”)
Brodak Kolar Kote (White) – (Coded “B”)
Coverite trim film (Blue) – (Coded “CT”)
Monokote trim film (Missle Red) – (Coded “MT”)
plus the original test;
Minwax Rosewood Water Base Stain
The first pic shows the test block – a pine 1 x 2 sanded with 220, with panels of each of the films in addition to the stain. All films were applied to the raw sanded wood. The three coverings were ironed on, instead of Windexed on, since it is bare wood. That shouldn’t affect the test, as the concern is adhesion of dope to the film, not the films to the substrate. The second pic shows the codes under each patch. Nobody is going to use dope over a large area of film, so the question is, do we get good enough adhesion to be comfortable with small dabs of trims and overlap areas?
The dope was clear Brodak thinned exactly 50-50, not that that is an ideal finish clear. But I figured any final clear of choice would bond to the Brodak, making it a reasonable choice for these “next layer” tests.
The stain was rubbed on, allowed to stand for 3 minutes, then rubbed off. I applied the first coat of dope about 12 hours after the stain application. Following coats of clear were added over a three day period, for a total of 6 coats of clear. Light sanding and tack rag between each coat, 400 after coats 1 and 2, 600 after coats 3, 4, and 5.
Each of the covering films was roughed up with 400 prior to doping, although I think Scotchbrite is preferred(?), but I didn’t have any handy. I figured 400 was good enough for a test. I first thought the trim films were known to be dope compatible and were included in the test more as comparative controls than a test. Then, on second thought, I was less sure so sanded the top half (only) of the trim films also. The sanding line is the inked line in the pics. Prep-Sol and tack rags on all films before the first coat.
I’ll do the tape pull adhesion tests on 2/19, having finished the final coat on 2/12. I’ll add some other details at that time.
Larry Fulwider