Killing waves

[Preston Herrick]

A buddy and I wet sanded my car today. Fenders and qtrs are looking pretty good but both doors with flat sections have slight waves visible when you sight down the length of the car. I'm thinking of throwing some 150 dry on my loooong Durablock and knocking the "highs" down and then working back down to 400 wet. I believe I have enough material on the doors.

Any tips or suggestions?

[Len]

That's how I would do it. The long Dura Block with guide coat works great in that situation.

[bodymanhelper]

A guide coat works good. you can see where your highs and lows are

[SHOWCAR FINISH]

I'd start at 240

[Preston Herrick]

Thanks guys. What's frustrating is I've used guidecoat throughout the process. You can't feel the waves - they're that slight. And my friend works in a production shop as a painter. I dry sanded through 400 and things looked good with wax and grease remover. As soon as we wet sanded with guidecoat 400 though - uugh!

I figured I'd have to use something aggressive like 150 to quickly and easily level them - but Showcar, you're thinking otherwise?

[Len]

Preston
The waves should be removed when you're working the filler not when working the primer. You should be able to use long boards to level the filler then prime then block sand using a 5" or 8" block and finer paper.

If you leave the waves for the primer to correct they will be much more difficult and time consuming to remove.

If you still have waves I'd recommend going back to a more coarse paper 100 or 120 to level the surface then hit it with some 220 before repriming.

[Preston Herrick]

Thanks Len. I thought I had removed the waves at the filler stage. Either I did or didn't, but in any case, there are now waves (very slight) in the primer - and it pisses me off. I think there's waviness where there is no filler. Like I said, you can't feel them - bare hand, paper towel, rag - they feel flat. I hope I'm not back to square one.

[bigrob24_7]

lens right on about leveling at the primer stage its a nightmare letting the filler cure is very important also.

[Preston Herrick]

The car was assembled on this last wet sand. So, since I'll be painting in pieces I started pulling panels and re-guidecoating and blocking with 240. They're a lot easier to work with on a stand. Anyway, once they were reblocked I guidecoated and wet sanded again with 600 (and a different block). The guidecoat disappears but what I'm finding is that the tiny waves or ripples are only where a spot prime transitions to the primer layer below. I can carefully sand till I'm blue in the face but you can see them at each edge which are well feathered and undetectable by hand. Must be a difference in primer hardness or type. I've done both fenders and completely reprimed with surfacer and will now guidecoat and wet sand again with 600 to see if they're gone. Doors are next. Then I have a couple of spots on the body.

I guess what I'm getting at is the defects are in the primer, not filler. The filler has had eons to cure.

[bigrob24_7]

a mistake ive been making is putting to much pressure on the panel while sanding..especially aflat door panel which will flex and move while sanding.

[Len]

The car was assembled on this last wet sand. So, since I'll be painting in pieces I started pulling panels and re-guidecoating and blocking with 240. They're a lot easier to work with on a stand. Anyway, once they were reblocked I guidecoated and wet sanded again with 600 (and a different block). The guidecoat disappears but what I'm finding is that the tiny waves or ripples are only where a spot prime transitions to the primer layer below. I can carefully sand till I'm blue in the face but you can see them at each edge which are well feathered and undetectable by hand. Must be a difference in primer hardness or type. I've done both fenders and completely reprimed with surfacer and will now guidecoat and wet sand again with 600 to see if they're gone. Doors are next. Then I have a couple of spots on the body.

I guess what I'm getting at is the defects are in the primer, not filler. The filler has had eons to cure.

You want to remove the waves using more coarse grits like 80 to 180 because, once you get to the finer grits, you'll have a tendency to "ride the waves" rather than level them.