[Roadsters] gas tanks and hardtops

[O'Farrell, Fergus P (AS)]

For minor cases of varnish build-up (and it does not sound like what the originator - Gary?  -was finding), here is what I heard from the 2-stroke outboard motor guys.

"Our first step for varnish build-up is we drain the tank and carb and put in the cheapest AM/PM unleaded gas and let it soak overnite. Those new gasses are so much like a solvent compared to old leaded gas, that that cures like 80+% of the gunk build-up problems."
Now they are dealing with 50/50 premix having the gas evaporate and leave the oil turned to varnish in the carb bowl and tank, but just a anecdotal note.

Hardtops:
Not sure where the porthole top was fabbed (most all the west coast dealer sold tops came from 2 fiberglass shops here in LA), but that vinyl texture is molded into the fiberglass skin.  Sanding to prep for paint is not a bad idea, but it will be hard (outside of some sort of media blast) to sand in the crevices of that texture, so it will be a challenge to get paint to stick consistently.   A mild (brass?) wire brush that lets bristles get into crevices might work well.  Rubbing beach sand on it might get into the small grooves too.
The real concern is if in scuff sanding you sand away any of the texture, leaving it smooth.  If you paint a glossy coating, that smooth area is going to stand out like a sore thumb.
Sand the whole thing smooth?  Good luck trying to do that evenly and not have a ton of whoop-de-doos. (technical term)
Plus a lot of itchy dust and noise, labor, etc.
Fill the grooves?  See lack of adhesion due to surface prep, and the top is going to get heavy, even if you use micro-balloons as the filler instead of a solid, like talc or cabosil or the common ones.  (talc is easily sandable, cabosil is not easily sandable.. and if this is chosen, PM me or read up about about safety measures using un-mixed cabosil)

Scuff sand, wipe with a mild solvent (ISO alcohol is a usual choice, doesn't leave a film) and rattle can a coating.  Multiple mist layers always ends up better, no thick layers.

Hope that helps, and was not too long winded.
Fergus O
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