PopaPork

iTrader: (4)

Been working on my FRC for a few weeks now off and on and I'm running in to a problem.

I used some fiberglass blondo to fill in the corvette letters and it did a wonderfull job but now that I'm sanding the things down I can see where the bond is and was on the plastic. I sanded the whole thing with 320 then moved to a 600, gave it some primer then did it again 3 times, and I still see the outline of the bondo.

Is this just one of the things I'm going to have to deal with or is there something I'm missing?

I plan on painting them flat black so I'm wonder if the little bit of the outline you'll even notice'

Tips/feedback would be a help.

Pork

keliente

iTrader: (22)

If you find out let me know. The same thing happened to me and it drove me absolutely insane. I really took my time with it too...and it was still noticeable.

PopaPork

iTrader: (4)

All you heads that's done this no ones got any ideas?

thesoundandthefury

iTrader: (3)

I run into this problem all the time with polishing due to inclusions in the metal, but it's the same concept basically: you have two forms of plastic that are of two different densities. When you sand, each plastic is getting worn down at two different rates. The denser plastic gets worn away at a slower rate and thus becomes a high spot in comparison to the surrounding softer plastic. What I would suggest is using a vibratory sander and focus it on the raised area(s). The flat plane of the vibratory sander will keep the sanding action even across the whole area of the high spots.

When you've gotten it to where it's pretty close, you can finish it with some high build primer, sanding with the vibratory in between each two successive coats and only stopping this process until the next coat you apply levels itself.

kerryt1

iTrader: (10)

build up the filler again so that it's the highest area, then sand with a very long sanding block along the longer direction of the part. theoretically, if the block is always resting on an area of original plastic, the filler can't ever get any lower than that (if you're using a sufficiently fine grit)

parbreak

iTrader: (17)

Best solution is to fill in roughly and sand roughly with the bondo or whatever you decided to use. Then go to an autobody store and get yourself some good "glazing putty" and use that as your finish coats over the lettering. It will take 3 coats sanding in between each and feathering each out as you go. First coat is to simply fill in all the pinholes the bondo left. 2nd is to start the feathering process and the 3rd is a very light finish coat and should be final sanded with about 400-600 grit. Final step is the use of a high build primer. Regular primer will take way too many coats to do properly. I use professional primers but Duplicolor high build filler/primer in gray will do just fine. YOu can use it to prime the whole cover if you like and then lay down a couple heavy "stripes" directly over the lettering and wetsand and feather those out until smooth.
Make sure to use an adhesion promoter before priming.


Bryan
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Mike02Z

iTrader: (13)

Bryan, I'm getting ready to try this myself and I have one question about the above. All the glazing putty I've seen is meant not to dry and stay flexible. Is there a different type you are refering to? When I hear "glazing putty" I think of the stuff used to set windows. Just want to be sure I get the right stuff.
Thanks!

parbreak

iTrader: (17)

The glazing putty is an automotive putty not the window sealant. Completely different stuff. I think some people refer to it as a finishing putty also. I use something called Metal Glaze and you can get it at Eastwood.

Bryan
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Mike02Z

iTrader: (13)

Ah..OK, gotcha. Thanks for the clarification.