Hey guys, New to the forum here. Looking for some advice. Heres the story:
I just finished repairing a set of Harley saddlebag lids that had a few small (1/4") holes in the top from an add-on. I filled the holes and feathered them out. Then re-glazed them to fill in any fine scratches or pinholes in filler; Re-sanded with 220 and primed. I then sanded the primer with 320 (Nothing visible) and based the lids (Nothing visible). Then I followed with 3 more coats of clear and still Nothing visible. Clear went on beautiful but I had a few small dust particles on one area. Finally, I wet sanded with 1500, 2000 and then buffed with 3M 3 stage buffing compounds.... BAM! Small circles where the holes were. My question is what did I do wrong? They never showed up until I buffed. The clear was like a mirror with no sign of repair until I buffed. How can I fix this??

Thanks in advance!!

Fairly modern lids I assume? Those would be ABS. What filler did you use? Just taking a guess so far.... buffer heat was enough to shrink and move your filler away from the surrounding ABS material..... well, unless they are older lids which is another matter entirely....

DarrelK wrote:Fairly modern lids I assume? Those would be ABS. What filler did you use? Just taking a guess so far.... buffer heat was enough to shrink and move your filler away from the surrounding ABS material..... well, unless they are older lids which is another matter entirely....

Nope, they are the older fiberglass lids. That's what has got me puzzled. I am really careful about buffing too. Burned through something along time ago, so now I am super careful to keep it low and wet.

Okay, here's the thing, I've worked on a few of the older ones with guys that have worked for me over the years. One set I saw just looked liked a regular open lay up mold style, nothing special however another guy had a set that I was sure were SMC (sheet molded compound). I told him to use our epoxy filler to repair those and he had no issues. SMC does require SMC compatible fillers (epoxy resins work as well) because the demolding compound is actually in the entire layup. Other than heat from the buffer.... that's all I got on it......

I would have feathered the top of hole out and down at least 1/2 the thickness. then used a fiber glass filler, Fibral by U-POL UP0700 works good. no 100% guaranty on this, or you could cut a couple small pieces of fiber glass cloth and use fiberglass resin. plain old body filler shrinks, put it in a hole and the filler shrinks but the hole doesn't then you have that nasty ring
Jay D.

badsix wrote:I would have feathered the top of hole out and down at least 1/2 the thickness. then used a fiber glass filler, Fibral by U-POL UP0700 works good. no 100% guaranty on this, or you could cut a couple small pieces of fiber glass cloth and use fiberglass resin. plain old body filler shrinks, put it in a hole and the filler shrinks but the hole doesn't then you have that nasty ring
Jay D.

I understand what your saying about the body filler shrinking but the clear coat was on for over a week before any cutting and buffing. And never showed up until after buffed. During wet sanding it was still not present. Only during buffing. Its bizarre.

I learned this the same way you are, a small hole on the dash filled it with filler. then after 4 weeks in the shop it got move outside the heat outside brought out the little ring. in your case, buffing you could have cut a little thickness off of the clear and added a little heat and that's all it took. i will almost guarantee it would have happened doing it the way you did.
Jay D.

badsix wrote:I learned this the same way you are, a small hole on the dash filled it with filler. then after 4 weeks in the shop it got move outside the heat outside brought out the little ring. in your case, buffing you could have cut a little thickness off of the clear and added a little heat and that's all it took. i will almost guarantee it would have happened doing it the way you did.
Jay D.

****...so my options are...strip it down and refill. Ugh. Any one know if aircraft stripper will harm these lids? Sanding would be a pain bc I painted over the factory color and I think another full round would be too thick and soft.
thanks everyone for the input.

I really don't like using solvent stripper around that fiberglass. If you do it work it fast to get the top layers off and then sand the rest off. I wouldn't let an M.C. based stripper get too close to the original gel coat/surfacer.

DarrelK wrote:I really don't like using solvent stripper around that fiberglass. If you do it work it fast to get the top layers off and then sand the rest off. I wouldn't let an M.C. based stripper get too close to the original gel coat/surfacer.

Thanks. Appreciate the info.