Hi, in a previous post I posted that we had just finsished shooting a base blue and then cleared with PPG 2042 clear on my firewall, There are some pretty big runs in the clear, and we are going to try and sand and buff it to get rid of the runs. If we burn through we are just going to Re-clear. My questiosn are;
1. what is the preferred way to prepare the surface to go over with clear again? the clear is only a few days old; we put on 1 thick coat and one very light coat.
2. I have heard it needed to be sanded; what grit sandpaper to use, ALSO my friend said 3M makes some "grey" scuff pads that would be good enough. does that sound okay?
3. WHat would be the preferred way to "clean" and prepare the surface? tack rags" some kind of mineral spirits?
THanks a lot! I always appreciate more knowledgable people replying!

You can use a gray scuff pad but I would recommend the usage of a sanding paste along with that pad. Just about every paint company makes sanding paste PPG's number is dx101.
Normally on the areas that will allow me I use a da with 800 grit to rough up the surface for clear. But when I cant use that method I use a gray scuff pad and sanding paste.

Sanding paste and a scuff pad is WAY faster, easier, more efficient and I believe prepares the surface better for topcoating.

If you use sandpaper then 1200 is what I would use.
If you need to rebase any spots I would rough up those areas with 400-600 grit

Thanks! pretty good info! you say "topcoating" do you mean "clearing" by this? also any other tips or tricks on cleaning the surface?

Originally posted by cody:
Thanks! pretty good info! you say "topcoating" do you mean "clearing" by this? also any other tips or tricks on cleaning the surface? Just do your scuff pad/sanding paste application, rinse off and then wipe it down with a tack rag. Then wipe it down with wax and grease remover. Then topcaot (clear). Correct me if I'm wrong Eric ;)

Yes topcoating is clearing.
If you use the paste its a real good idea to wash the area with water after you are done sanding.

Allow the area to dry and then blow out any cracks, places that water can hide.

And as Texas said tack it off, wipe it down with a surface cleaner like PPG dx330 or dx220 I believe the number is. Mask up the firewall and before you apply paint I like to reclean it with cleaner followed by the tack rag

HI, We used the gray scuff pad with sanding paste, and it worked great. However where we fixed the drips we sanded through!! my friend said he will try and touch up the spots where we went through, or end up spraying the whole thing again with base which i don't want to do. question now are;
is it okay to spray over the entire thing even though there is clear on it(has been scuffed down)
also can we just scuff as we did the areas that need to be rebased? or do i need some heavier sandpaper? they are pretty small spots.
also i got some PPG 330 degreaser@! thanks for the help; it has been dead on!

Eric will know what your best solution will be. graemlins/thumbsup.gif

ttt

You can mist the entire firewall with color without any problems, in fact it should lay down really nice. good luck with the clear this time, no drips smile.gif

Thanks, but what do you mean by "mist" sorry i am a beginner when it comes to this stuff, and don' want to mess up! I am gonna have the heater blasting and the work lights on(hot) for awhile before we spray! to get it hot graemlins/hurray.gif

Just put enough base to cover where you sanded through and put a light coat of base on the entire firewall (mist) this will give the clear something to hold on to.The only spot you have to watch is where you sanded through if you get the color too wet it could lift just use light coats and let it sit a while in between coats.
You don't have to sand the firewall with anything the grey scotchpad will be fine,make sure you put enough base over entire firewall to cover any scratches left by the scotchpad or you will see them through the clear. Mike

Thanks guys! we just put on a light coat of base and then recleared it. but when we put on the base suddenly some new drips started showing, but they werent' in the base they were in the old clear! we sprayed 2 light coats of PPG2042, and then ran out of it so we put one last somwewhat thick coat of PPG2055. It came out pretty nice! There are still a few previous drips that we missed, but most of them you will never see once the engine is in. also it was still pretty cold in the garage but we had the dual halogen work lights on it which helped some. ALl in all you can still spot a few mishaps, but they will be covered up. It looks great! i will post pics soon. thanks!