best painting technique for 1-part paint in tight spaces?

What's the best technique you guys have found for getting 1-part poly smoothly painted into tight spaces, like foot wells in a surf ski or around hardware, where a roller won't fit?

 

Welcome.
Try a brush. Wear gloves.

 

Touche' Foam brush or bristle? Tried with nice angled bristle brush first, but that seemed to leave a lot of grain... haven't tried sponge yet.

Follow up question: is it practical to do a two-part paint over a one-part?

 

You may just dab it on with a natural sponge. No linear brush marks that way; just texture.

 

This boat is a beater, so a great boat to experiment on with glass and painting...

Follow up question: can you do a two-part poly paint over a one-part?

 

Edit: No.

 

Try the triangular sponges sold on the make-up isle.

It it usually not recommended to use a two part paint over a single.
The two part frequently has solvents that attack most single pot paint. If it doesn't have immediate problems then all is almost OK. You won't get the adhesion benefits of the two part because the over painted single will fail under the two part. Kind of like painting over tape. Looks good until the tape lifts.

 

FUNNY, it's almost as though building a boat and gelcoating and painting it is a complex process that requires a great deal of skill and planning. Who'd have thought. I sure bumbled into this, but it's been a great learning experience on a found boat. Nothing to lose and turning out a bit better than expected. Lots of things to improve on next time.

 

If brush leaves marks; use a capful of thinner.

 

@fallguy does it need to be a specific thinner and what is the % per 100 gr for example?
Can I use acetone as a thinner?

 

It should be specific thinner for the paint. Recommend about 5% off the cuff, but manufacturers usually offer recommendations.

glass test if in doubt

paint on clean piece of glass no thinner
Then 5% thinner
Then 10% thinner

see what looks best, simple as that, 10% thinner will cost some sheen, on my boat; used some thinner on last coat because it lays down so much nicer

 

check with your paint store as there are product specific FIRMNESS of brushes as well. When you say bristle, are you meaning a bristle brush for oil base as compared to say a nylon brush for latex. There are also some for varnishes
and stain that are softer and will feather out paint easier and with less texture/brush marks. Mind you if your one part paint is quite thick, an extremely soft brush will not move the paint around.
The recommended instructions for two part poly paint, (when you cannot spray) is roll and then feather with a brush. You can buy rollers down to a couple of inches which will get into most areas. The advantage of a roller is that
you can roll the paint in all directions and get an even coat before you feather

 

if it's a really tight space get a fan blowing air in there, the fumes can be nasty, so nasty I had slight chemical burns to my legs through my overalls, lucky my head was above the chemical level..