Bondo & Sanding tips

JoeB1355

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So I am not the best at this -- I've fixed draywall holes with spackle scratches on cars cabinets and now I am trying some bondo on a coin door

Everything usually goes as planned and I get a decent result -- but I can always see my repair

so I must not be good at this and need some tips

How can I bondo something sand it and paint and the repair be invisible? Body shops do it why can't I.

Its always looks smooth feels smooth but then I paint and I can see it


my steps I did on a coin door I had

some drilled a hole in it and it was mucho rusty and dented -- so I wire brushed it down to the metal sanded it with 150 then 220 grit

epoxed a metal square on the back for the hole repair

then I bondo'd over the hole and dents, sanded again 150 then 220 -- its came out ok -- just not perfect -- I can see it even after 3 or 3 coats of spray paint

What's the autobody secret?

Should I remove the paint and start all over or can I just work over my last repair

Like I said I tried fixing scratches on cars too -- same ok result -- I need some secret power here to make my repairs invisible!
 
in autobody work we use over 1000 grit :D

we also have something called icing (it's expensive) that is a super fine finishing filler.

I haven't started any of my cabinet restorations that entail repairing the sides (yet, but soon tho).

one pointer i can give u is to put it on and try and make it as smooth as possible before it dries (think skin coat/covering). if you put to much on you can sand it down before it fully cures making it much easier to remove large amounts of bulk bondo.

also a good body guy won't use any bondo. but that's because metal is much more forgiving than wood.
 
Primer over the repair...sometimes two or three light coats..then put your final color coats on it.....The primer acts as the blending agent and then you will get a nice even finish with your final paint color.
 
Primer over the repair...sometimes two or three light coats..then put your final color coats on it.....The primer acts as the blending agent and then you will get a nice even finish with your final paint color.

I got 4 coats now... Here are some pics -- well see if you can see what I see
 
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4 coats of what...I don't see any primer...unless you have pictures I'm not seeing....you need to have your repair level and even with metal...what I do is feel it with you hand while not looking when you can't feel any ridges..then primer with a couple light coats..and then you won't need four coats of paint...
 
I got 4 coats now... Here are some pics -- well see if you can see what I see

yup you got a few low spots, sand them out the best you can and hit em with the bondo. you can also get an autobody hammer and dolly and try and hammer those low spots out from the opposite side (if that's possible). I wouldn't worry so much about the inside as the outside.
 
after pic

not sure if you can see -- I posted the before pics so you can see where there hole and maybe dents
 
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I put circles on the pic so you can see the spots I bondo'd. Maybe its just this Rustoelum satin -- it looks nice but it has to kinda level I think. Its shows all the spots... but looks nice if its perfect
 
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Yeah looking at your before photo with bare metal repairs the indentation by the lock hole just isn't filled enough and sanded smooth...as far as the bottom that is pretty good dent..that is more of what your seeing..not the fill above above...dents are tough when they are that deep and pronounced to get them completely knocked out..and if you don't do the repairs smooth no amount of paint is going to cover that up...the paint will simply settle into the indentation and still show. All you can do is knock out dents best you can and then make sure the holes and imperfections your filling are sanded smooth..sometimes it takes several coats and time to dry and sand..dry and sand to get it just right.

I still recommend a light coat or two of primer to...it helps adhere the paint better and you get a better surface for your final coat to lay on...you will need less coats with a good coat of primer sanded prior to final paint being put on...
I've used same paint as you..its all in the prep work...do that right and the paint job will look fine..rush it and you will get less than desirable results.
 
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You undercut it pretty good...
Primer is made for leveling..not filling

Honestly...if ya want to make it look 'perfect'..skim the thing again. I would do the entire bottom half then block it. On a small spot like a coin door sometime a wooden paint stick will work nicely. I used them in the body shop to get 'lines' straight.

Also..I would use courser paper if available...80 to start...make it straight...Don't over sand it.

Then block it with your 180-220 to remove the scratches.

Straightening something with 220 to start is tough.

Remember you have to feather the dent into the 'good' part of the door...thus your mud work should end up almost twice the size of the original dent.

Make sense?

Good luck!
 
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