jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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ive sanded a new bumper down as good as i can, and just put first coat of primer on and you can still see quite a lot of the sanding lines.........what can i do about this? wait for the primer to dry and sand again? or will high build primer fill the lines in?
[Edited on 15-06-2010 by jon-valver]
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daymoon
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Registered: 1st Aug 08
Location: Selby, North Yorkshire
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se finer sand paper to what u used before.
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shaunmods
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Registered: 12th Mar 07
Location: Glascote, Staffordshire
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What grit did you finish it off with before priming?
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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ive just used like 1200 on it and it felt proper smooth to me, but i can still see the lines from when i used rough sand paper underneeth?
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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so 1200 before priming. but i could still see the lines kind of from when i used 80 grit....but it felt well smooth....
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shaunmods
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Registered: 12th Mar 07
Location: Glascote, Staffordshire
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Did you go from a lower grit like 80ish straight up to 1200? If so you need to need to gradually go up through the finer grits. I tend to go 240, 600, 800, 1200 so its getting smoother and smoother with each change  Once you've primed it go back over it with the 1200 to get the primer nice and smooth before paint as well
[Edited on 15-06-2010 by shaunmods]
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AlexW
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Registered: 25th Oct 08
Location: Essex
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Also use guide coat, like a yellow or black paint, then sand through it, any bits that are left black/yellow are bits that need attention.
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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okay will do, will high build primer be better aswel? cos then it will hopefully fill the sanding lines and then i can just go over that with 1200?
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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ah good idea 
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shaunmods
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Registered: 12th Mar 07
Location: Glascote, Staffordshire
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quote:
Originally posted by jon-valver
okay will do, will high build primer be better aswel? cos then it will hopefully fill the sanding lines and then i can just go over that with 1200?
if the scratches are quite deep the 1200 isnt going to be able to remove them. If it was me I'd drop back down to a lower grit like 600 to get the deep ones out then go over it with 800, followed by 1200 to get it smooth. It depends how bad they are though really. See how you get on and if they are still there try some high build
[Edited on 15-06-2010 by shaunmods]
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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yeye cool will do, well ile take a pic when i get round to duin it, need to wait till friday now though to stock up on primer and sanding papers.
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Twiggy
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Registered: 15th Oct 04
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Sounds like you will have nothing left to paint! 
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DaveyLC
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Registered: 8th Oct 08
Location: Berkshire
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quote:
Originally posted by jon-valver
so 1200 before priming. but i could still see the lines kind of from when i used 80 grit....but it felt well smooth....
80 - 1200 grit..
FAIL!
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Callum
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Registered: 17th Dec 08
Location: Renfrewshire
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quote:
Originally posted by DaveyLC
quote:
Originally posted by jon-valver
so 1200 before priming. but i could still see the lines kind of from when i used 80 grit....but it felt well smooth....
80 - 1200 grit..
FAIL!
Hes only asking for help, we all make mistakes
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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i did not go from 80 to 1200 you burk. calm down........i used 80 then 300 then 400 then 800 then 1200......i cant do it rite though lol ile post a pic up in a sec, will hi build primer fill the lines and then me be able to get a smooth finish of that with for example 1200 grit ontop of the high build primer?
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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in the first pic you can see the lines and ive bin sanding for ages and there deep......so would high build primer do the job or am i going to have to use like 80 gritt again? i think its because i started sanding doing back to forth strokes like a tit. cos ure supost to do circular motion yes?
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shaunmods
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Registered: 12th Mar 07
Location: Glascote, Staffordshire
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Ahh right so you're smoothing the texture on the black plastic part of the bumper. It that case yes high build primer will help. I wouldn't worry too much about doing circular motions either mate. Just back and forth will be fine, thats how I've always done it. Going by the photo I'd drop back down to 600 grit and give it a good rub down with that to see if you can get the worst of the lines out, then do the same with 800. After that give it a few coats of high build primer. Once thats dried nicely smooth it down 1200 and see how that looks.
[Edited on 15-06-2010 by shaunmods]
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DaveyLC
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Registered: 8th Oct 08
Location: Berkshire
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Give up.. Its all going to fall out..
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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DaveyLC . why all the putting down dont post on here if you dont like it simple LOL
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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and there pretty deep mate so mite try a bit lower grit like 200 or sumthing and then start over....ile take some more pics after ive had a crack with the sander lol
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ed
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Registered: 10th Sep 03
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You'd use 80 for shaping filler and stripping paint on metal, it's far too coarse for sanding plastics as it will leave deep scratches like you've unfortunately got. 1200 is far too fine to repair the problem, you'd use that to get rid of deep runs in lacquer or paint.
For prepping you'd want to start off with some 350 and then move onto some 600. I'd suggest trying to get the worst of the scratches out with some 350 or even 200 then tidying it up with some 600. You could then go over it with some high build primer which can hide any of the remaining scratches after you've sanded it with some 600 again...
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jon-valver
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Registered: 28th Mar 10
Location: West Yorkshire
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yeah, well ive just been over some scratches with 80 but on a sander and its got rid of them, but ive ran out of paper lol so ile get rid of rest with 80 then move to 350 then 600. ile post summat if owt goes wrong ect..
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Tom G
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Registered: 4th Aug 08
Location: Cheshire
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quote:
Originally posted by DaveyLC
Give up.. Its all going to fall out..
What a prick you really are.
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Joe
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Location: Hesketh Bank, Lancashire
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Dave likes to be a know it all patronising cunt.
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