fixing run in basecoat

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PostPosted: Sun Jul 15, 2018 7:41 pm
Hello all, i did some small rust patches in the bedside of my truck, got it all primed and went to lay the base.. ended up laying it on too heavy and it ran. i waited for it to dry (took forever to flash w/ high humidity) and sanded it out. but even after sanding it smooth i shot a few more coats of base and you could still see like the outline of the run... so i started sanding again. all the way down to the primer ended up going through the primer.

so now im in a pickle. im through the primer but its not like it was over my filler, only to the old paint below. the primer was light in this area, around where it was feathered out.

now what should i do to fix this? I should also mention this base is going to be sitting for atleast a week before im able to work on it again.

im worried where i sanded it out i may have dug a hole that is going to be seen if i base it again.

ive painted plenty of times before but im used to S/S and painting heavy equipment.
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PostPosted: Sun Jul 15, 2018 11:27 pm
Yep, your going to have to prime that area hopefully you have some hi-build primer. spray a few coats on then guide coat it and block it. you will have to respray all the old base coat. light med coats this time with plenty of flash time in-between. you should be ok to shoot base right over the old base no sanding. I know they say not to sand base but its set for week or so. I would wet sand it with 500-600 and recoat, this will get you back smooth again also. lets see what others have to say.
Jay D.
they say my name is Jay

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PostPosted: Mon Jul 16, 2018 4:42 am
It's not very often that I get a run in base (but it has happened :knockout: ). More likely the first coat of base shows up a fault that couldn't be seen in the primer and that needs a little sanding down/rectification.

I don't have time to wait days. If I see something then I'll address it before progressing. I've used thinners to wipe off base and I've sanded base. The trick is to get the edges feathered out so the repair isn't visible. Sometimes there is no choice but to reprime that spot - it's a call you have to make at the time and based on that specific problem. Either way, the car doesn't leave the booth and usually rectification can be done within 30 minutes or so, before proceeding with the final coats. I usually hit the area with heat lamps to dry off what's there so that if I have to sand it won't tear. When sanding I go gently, with as fine a paper as will do the job so as not to create more problems. I usually dry sand but you can, despite what they say, wet sand - just leave the surface clean and dry before proceeding with further coats of base.

If sanding out a run, whether in base, 2K or clear you must use a block. In OP's case the solution now is to reprime that spot, rub back and then scuff the rest of the base coat with grey scotch. The base that is on there now will be outside of its recoat window and will need the scuffing to provide mechanical adhesion.
Chris



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PostPosted: Mon Jul 16, 2018 5:57 am
thanks, ill re prime and block it out. hopefully all goes well.

my brother does auto painting for a living maybe i can get him to come shoot it this time.. haha



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PostPosted: Sat Jul 21, 2018 8:15 pm
Why not try again? What's the worst that can happen? Another run?

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