Filler before primer

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PostPosted: Wed Jun 08, 2011 3:28 pm
So I'm going to get my truck to the paint booth in the next couple days for some epoxy and a couple coats of high build primer.

The bed had some small dents on the bed rails that i've been slowly filling in with filler. Pretty much skimed th entire top, sanded, more filler, sanded ect until it's fairly smooth (first time using filler, so it's been an expirence)

Question is how smooth does filler need to be? I've been forming it with 80, then hitting it wiht 220 to smooth it out and feather it, but there's still some spots that i've been wondering about. We're not talking dents that aren't filled in,but some spots that the filler hasn't smoothed out entirely.

How much can you smooth it out after you primer it, and if it's still not completly level after you put the primer on it, i'm guess i can do some "touchups" with some more filler if necessary?


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PostPosted: Wed Jun 08, 2011 4:48 pm
220 is good i usualy just go down to 180, unless it a dark color. its hard to tell what you mean buy the spots that haven't smoothed out yet. if you still have some low spots keep filling and blocking untill its smooth. when your finishing off your bondo you can guide coat it to see where your at. also your filler primer will smooth it out alot :) filling can be a hard untill you get a little experiance at it
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PostPosted: Wed Jun 08, 2011 5:00 pm
primer will fill scratches that aren't too deep but that's about it really.
get your filler as level and as smooth as possible,what you don't want is an edge where the filler meets the surrounding metal or paint

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PostPosted: Wed Jun 08, 2011 7:04 pm
On larger fairly flat surfaces use at least a 9" sanding bock. Spread your filler quite a ways past the dent you're trying to fill so there is plenty of room to feather it into the surrounding area. Use a coarse grit like 80 and block sand most of the filler off. Repeat until you see that all of the filler is being sanded (i.e. no low spots) then skim coat with filler and let cure. Apply a guide coat and block sand with 180-220 grit until guide coat is gone. The guide coat will remain in any low spots showing you where the problems are.
Since you are apply epoxy first I wouldn't go too smooth on your finish sanding. 180 should be fine as the epoxy needs something to grip.
The above process is very similar to what you will do with the high build. Spray it on, sand most of it off, spray it on again, guide coat, etc.
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