what to use for filler? smoothing before paint

ok I"m prepping the transom of this runabout (glass boat) for paint since it's a little rough looking. The previous was rotted so the previous owner removed the wood and it has now been replaced and very sturdy, (gelcoat and fiberglass wasn't removed just the thick inner core)

in the process there were several 5/8" holes drilled to put bolts through to clamp the boards and glass together to get a good solid bond during gluing.

now I"m finishing this and need to know what to use for filler? I"ve done some body work on autos but this being near the waterline if not in I don't know what to use. I got some epoxy putty (goop) and filled the large portion of the hole from the outside and plan to fill it the rest of the way inside with resin once I get my order in the mail.

so once I sand this stuff there will still be some minor imperfections.
so what do I use for filling this? Epoxy resin? then sand and paint?
I've got a quart of interlux paint I"m planning on trying brushing over this.
also is the thinner needed for brushing or will it work without?

 

You can make a fine filler with epoxy by adding microballoons, that way you don't have to buy yet an other product.

 

I don't have any microbaloons either unless I don't know what they are...
I have fine sawdust from rot-doctor that the previous owner bought when he bought the epoxy stuff. but the epoxy seems to run and sag quite a bit unlike conventional fillers for body work that don't do that. not trying to push using bodyfiller just what I've had experience with. aren't microballoons something you purchase also?

 

Yes,

Look here:

http://www.westsystem.com/webpages/productinfo/guide/index.htm#additives

or any other producer.

 

Thicken the epoxy with the microballoons to a peanutbutter consistency. Use the slow hardner, our Texas heat will kick off the fast stuff WAY too fast in a thick application. You may or may not need brushing reducer depending on the paint. Interlux polyeurethane- definitely need it, enamel- not as much, if at all. Roll it on with a foam roller, then "tip off" the bubbles by very LIGHTLY dragging a foam brush over them, and it'll look like a spray job, smooth and glossy. Good luck.

 

Epoxy with micro balloons a.k.a. phenolic micro balloons will do well. Its a dark reddish brown colored filler. We have some with a little silica mixed in to keep it from sagging. You could use wood flour, but only if you like sanding

Joel
Boatbuildercentral.com