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Wood Filler Over Primer?


q83

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Hey guys,

I just finished sanding this body for the second time. I spent about 3.5 hours today sanding, filling the grain, and painting (the primer coat), and I *JUST* saw a small dent on the backside of the guitar. I never missed it before, because it wasn't there before. I'm guessing either I accidentely hit something while I was moving it over to my painting area, or small rocks fell from the sky through my garage. I tried the method of using a soldering iron and water to raise the wood, but I think the fibers are broken and I can't get it back. Now I already painted the primer coat, and I have some rather crappy, and old, wood filler. Would there be anything I could do to solve this problem without having to re-sand and re-fill?

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Keep filling the dent with primer until its just "proud" of the surface, then sand flush and resume your finish job. You can use an eye dropper or just take a pencil (or similar pointy object), dip in the primer, and let a drop fall into the dent. I've used filler primer quite a lot to deal with similar booboos on boat hulls. :D

Edited by Southpa
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Keep filling the dent with primer until its just "proud" of the surface, then sand flush and resume your finish job.  You can use an eye dropper or just take a pencil (or similar), dip in the primer, and let a drop fall into the dent.

Although that will work, it is going to take a looong time for the primer to dry. If you start sanding too soon it will just fill the sandpaper and leave a messy looking finish. The body filler would be my weapon of choice.

Just my $0.02

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Ugh, sorry for the second consecutive post but I miss the edit button as well. Anyways I exadurrated in the last post, the size of the dent only has a diameter of about 1/8", it's quite smaller than I was thinking. If you guys think I should drop in the white primer, let me know. Also, I wanted to spray the guitar the solid color around 8pm tonight, which would give it 8 hours to dry. Think that would be enough time?

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Ugh, sorry for the second consecutive post but I miss the edit button as well.  Anyways I exadurrated in the last post, the size of the dent only has a diameter of about 1/8", it's quite smaller than I was thinking.  If you guys think I should drop in the white primer, let me know.  Also, I wanted to spray the guitar the solid color around 8pm tonight, which would give it 8 hours to dry.  Think that would be enough time?

Tough call. In that timeframe I'd fill it with body filler. But I have a bias to that as you can prob tell. Whatever you use dont rush anything. Depending on the type of primer it can take a while to dry though. A 2 part filler will be dry and sandable in 30 min.

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Ugh, sorry for the second consecutive post but I miss the edit button as well.  Anyways I exadurrated in the last post, the size of the dent only has a diameter of about 1/8", it's quite smaller than I was thinking.  If you guys think I should drop in the white primer, let me know.  Also, I wanted to spray the guitar the solid color around 8pm tonight, which would give it 8 hours to dry.  Think that would be enough time?

Tough call. In that timeframe I'd fill it with body filler. But I have a bias to that as you can prob tell. Whatever you use dont rush anything. Depending on the type of primer it can take a while to dry though. A 2 part filler will be dry and sandable in 30 min.

Yeah...

I tried the filler trick. I'll wait till it's dry. I can always paint it tomorrow night. I'm not really in a rush or anything, I have a month left before I should start the clear coat if I want it finished in time.

Thanks for the advice though.

I've got a bunch of P400 and P800 sanding sheets available... which do you guys recommend on primers? My friend, who has done some completely INSANE paintjobs (including a very well done recreation of the Crash-3), tells me all I need for properly sanding paint is 400 grit, but I've read to use 800. And veeeery lightly.

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Ive had problems danding with 800 in my early painting experience. Ive had paint lift from the primer because there wasnt enough bite. 400-600 grit should be enough. If its a metallic finish the 400 will appear scratchy because the particles will follow the scratches.

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am i the only one that realizes that auto body filler is not meant to be used over paint?

it even says in the instructions to make sure the surface is free from oil,grease,and paint.

EVERY time i have used it at work over primer it has come off...i think once you finish it the only thing holding it on will be the top layers of finish...i think you should have listened to southpa...

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am i the only one that realizes that auto body filler is not meant to be used over paint?

it even says in the instructions to make sure the surface is free from oil,grease,and paint.

EVERY time i have used it at work over primer it has come off...i think once you finish it the only thing holding it on will be the top layers of finish...i think you should have listened to southpa...

We're talking about a little dimple here. I have NEVER had filler come off......EVER. If you slather it on over paint you are asking for trouble. But a small dimple? You havent fixed many cars have you?

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You havent fixed many cars have you?

i am not going to waste time arguing with you about this...but know that at my job i keep a can of auto body filler in my truck,and i use it up and replace it at least once a month.

my disagreeing with you does not mean i have no experience.

regardless...do it right or do not do it at all...that should be everyone's goal...shortcuts are generally done because they are considered "good enough"..even though they generally are not actually good enough.

But a small dimple?

a small dimple with nothing for the bondo to adhere to?...yes

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Either is applicable, but the first rule of thumb is to try to stay with whats already on there to maintain a homogenous surface coat. Thats the best way to make sure, just in case the foreign material decides to expand, shrink, loosen etc. Whatever is used, its important to scuff up the insides of dimples and dents to ensure proper bonding. I've spent many hours prepping surfaces for filling, having to scuff all the "shiny" dimples and low spots with a tiny corner of sandpaper after board sanding. :D

Edited by Southpa
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Wes is right. Bondo is made to adhere to a clean bare surface. But with a small area like that it probably, and I mean probably, won't be an issue.

If the area is small enough, and if it's compatible with your paint and primer, you could try spot putty. You know, the red stuff in a tube that's lacquer based. It's made to be used on top of primer, mainly for pinholes, but you have to judge if it will work for you.

As always, test this stuff in an inconspicuous area before you commit yourself and screw something up. If it comes out bad it ain't my fault. :D

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I'd drop fill with primer. The bondo might work, but I know the primer will. Sounds like you don't NEED it done right now anyway.

Somthing to get clear with people who don't work with it too often. Not all fillers are created equal. Bondo is NOT A QUALITY FILLER! It is perhaps the worst. A good filler has to have a base and a hardener (I know i know bondo has that but whatever). For topcoats and imperfections like this it's best to use a fine filer in a skim coat making sure the area is roughed up first.

Definition of a skim coat is just enough to fill the imperfection + a little bit for shrinkage in drying.

For topcoats on cars and guitars if need be I use Evercoat glaze coat.

Glaze Coat

Just search for part #100417

Its is very fine almost a thick paint consistancy

And for those who are doubtful about sticking to paint....I can't speak for bondo because I dont use the junk but I'm assuming from wes that it does not stick.

The back of the Glaze coat container reads "For use over body filler, fiberglass, many plastics including SMC, metal, two component primer surfaces and oem topcoats. I have used it on fender, samik, ibanez and peavey paint with no problems 2yrs + later. And I filled some pretty big holes. Ibanez for example was stripped by some guy with a blowtorch.

Im sorry if im off on a rant but it just floors me when people assume you know jack because you have less posts. There is a world before PG people!

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