Repair finishing

I just got done repairing the damage done to my fin and sanded down as much as I dared. I don't want to sand all the way down, due to the way it split along the ply. Now, the question is...do I put a layer of primer on there, or should I just reapply the finish coat?

Need a little more detail on the repair before I could comment.

But off hand I'd say prime first if you sanded down to bare wood. If not just put the new finnish on.

sandman

Well, the fin had been fiberglassed, but split anyway. It is a very shallow split that goes along the grain (i.e. if you try to pull the fin to the side rotationally, the fin would start to pull away from the thin layer that started to split off). The split starts about halfway between the body tube and the fin edge and goes towards the body tube as it gets deeper. I repaired it by pulling the fin aside a bit and drizzling some heated epoxy into the split. The reason I don't want to sand it down to the wood is because the top layer that started to split off is VERY thin in places and I don't want to start sanding through any wood. I sanded down as far as i dared and some bits of it are bare fiberglass, some still have a little bit of the black finish coat on them, and some have the primer showing.

I wish I could describe it better, and I hope I got the picture across.

Originally posted by KermieD
I just got done repairing the damage done to my fin and sanded down as much as I dared. I don't want to sand all the way down, due to the way it split along the ply. Now, the question is...do I put a layer of primer on there, or should I just reapply the finish coat?

Click to expand...

If the damage is minimal, I will sometimes just reapply finish coat. For anything that requires strengthening, reapplying glue or epoxy, filling with Bondo, etc. I tend to go ahead a prime again, so I can make sure my patch is smooth and will not show when repainted.

The big problem for me usually is that with all the different brands of paint I have, I occasionally get a reaction with some brands of primer when sprayed over the finish coat from the original paint job. If you find this to be a problem, one way to solve the problem is to use an acrylic primer such as DAP. I have also had good results using Kilz primer on repairs (although I do not believe it is an acrylic paint).

The cheap primers I buy (and really like in general) -- like Kmart's Fresh 'n' Easy brand, is notorious for crinking finish coats.

Have fun experimenting!

No time for experimenting. Launch is Saturday. I have Krylon primer, and that's about it. I wouldn't mind flying the rocket nekkid, but we're talking about flying one with tattered clothes and that just won't do.