[RodFather]

I have been reading the forum trying to find out how to fix my problem. I have found some good advice for the future, but I haven't found my situation yet.

I skim coated my car and repaired some things. The clerk at my local paint store told me that if I use his High build primer (2k I think it is) I will only have to finish my bodywork with 36 grit sandpaper and his primer would fill the rest. Being the trustworthy person I am I did just that. It now looks like I painted the car with a brush.

I know to go at least 180 grit in the future I have should have read the post before I started. How do I fix the problem? Do I need to strip the primer off before going with a finer sandpaper at this point?
Thanks,
Brian

[hemi43]

By reading your post I assume the car is not painted yet!!! If it's not, it will be fine. What happened ,is that after you laid the primer over the 36 grit scratches, the primer shrunk thus revealing the scratches. When I paint something like a bike tank or something that's other than a daily driver, I let the high build primer cure for 2 weeks before blocking. Some might argue that it's overkill, but this way I'm guaranteed that all the solvents have been released from the primer. Dan
www.geocities.com/dantechfab

[kenseth17]

No, you don't really need to strip off that primer, but probably will need sanding with around 180 and another round of primer. Guide coat the primer and try to work out the scratches some when blocking it. Usually you get your filler worked out to 180 grit or 80 at least before 2k urethane primer, but when doing it in somewhat of a production shop, you can miss taking out all the 36 grit scratch in the rush to get it in primer for paint that day. Luckily you have the time to go over the primer and block out and apply another round, which is what really should be done regardless on bodywork areas. A 2k spot or glazing putty should be okay to use over the primer also if you find pinhole are have any really nasty sandscratches that won't work out to the point that primer will fill or may show up as the primer shrinks a little.

[MARTINSR]

Brian, what primer is it exactly? "2K" means everything that uses a hardener, urethane, epoxy, enamel, etc. So, what is it exactly?

When you say you "think" it is 2K did you apply it? If you did, and it used a hardener, what kind of hardener?

It sounds like the others are right on target that it is likely a urethane and it shrank up. It needs to be blocked and primer reapplied. Not harm done, but you are asking the primer to do a lot (filling 36 grit scratches).

HOWEVER, another "2K" primer, Polyester (uses MEKP as a hardener in a small tube) will fill 36 grit scratches without even working up a sweat.

Brian

[RodFather]

I actually don't remember the name of the primer I know it said 2k. I did apply it, but left the leftovers at my in-laws house.

The primer is black so would I guide coat it with a silver or white?

[Bee4Me]

If you use a gray primer,you already got it guide coated. Hehehe.

Any lighter color will work. I'd stay away from a metallic of any color though for blocking. I'm not sure "if" 3m's dry guide comes in anything other than black but might be worth asking about as it's a great guide product and no waiting for it to dry.

[kenseth17]

What size tip in your gun did you use to spray it on? A urethane high build primer will probably shoot with 1.8 tip, or so, better with reduction, I don't haven't really used much for polyester primer, but would think you would need a pretty big tip size to spray it, and it would be activated with the mek like brian said, a tube of liquid hardener like is used in fiberglass resin, and the urethane would most likely have activator in a can and be mixed somewhere around 4:1 depending on brand, Epoxy primer generally isn't really a thick primer with a lot of fill, the ones I've used have been 2:1 or 1:1 and you would know it when you went to sand, because they don't sand well and clog up the sandpaper, but it may not be the case with all brands.

[hemi43]

Hey Ken!! Were you out of breath after writing that?? I was after reading it!!! LOL. Just kidding. I spray polyester primer with a gravity gun with a 2.5 tip. It works great!! I think this gun was made for shooting gelcoat. I spray my high build urethane trough it too with excellent results. Dan
www.geocities.com/dantechfab

[kenseth17]

Yeah, I tend to make run-on sentances when I get typing in a hurry. I was just trying to help identify what he used. I am guessing it is urethane if it said high build and he didn't use a gun with a huge tip to spray polyester, and the way he described the scratches. Figured he would be able to identify it by how it was activated and somewhat by ratio and the propertys of the primer. The fact it said high build on the can makes me believe either polyester or urethane, most likely urethane if the activator was in a can and the ratio was somewhere around 4:1 and the tip size that is in his gun isn't up in the 2 range. I don't use polyester, but being basically bodyfiller in a can, without a bunch of reduction would need a pretty hefty tip.