I'm finishing an exterior door for some clients and recommended a high quality marine spar varnish. Does anybody know if spar has the same rubbing out qualities as regular interior varnish? Is there anything special I should know?
From contributor R:
I'm not a professional finisher, but have done quite a bit of work on boats. Perhaps these comments will hold you until a pro weighs in.
As far as I know, you cannot rub out a spar varnish. Spar varnishes are tough, but not hard. Their elasticity is what allows them to move with the wood in the harsh outside environments. The counter to this is that because they are not hard, you can't rub them out.
Then I would use 3M Imperial Microfinshing compound followed by Finesse-It III both on buffing pads. Incidentally, you should wait a long time prior to rubbing out spar finishes as they continue to dry for weeks leading to reverse sanding scratches after rub-out as the finish continues to shrink.