Wet Sanding vs. Compounding Alone

[Justin Murphy]

I've been wanting to ask this question now for a long time............

If the paint condition is severely swirled and full of RIDS, is it more efficient to wet sand and then buff out over compounding like crazy with wool and multiple passes?

Time has to be saved by wet sanding first in my opinion. I wonder, in the end, which of the two will actually remove the most clear coat?

Pros chime in please!!!

[BlueZero]

Re: Wet Sanding vs. Compounding Alone

Pros chime in please!!!

I'm not a pro but...

I would bet that to get the paint to the same point of defect removal both methods would remove the same amount of clear. Wet sanding would be the faster of the two options for severe defect removal. Also with wet sanding you can just get the area around the scratch, minimizing clear removal over the remainder of the panel. Someone please correct me if I'm wrong but I believe that is refereed to as feather sanding.

Just remember to try the least aggressive product and/or method first.

Okay, back to the pros now.

[Mike Phillips]

Re: Wet Sanding vs. Compounding Alone

The problem with wet-sanding is you have limited film-build to work with and if you're working on factory paint it's going to have been baked-on at the factory and have reached maximum hardness.

The thin factor and the hard factor make the sanding approach much more risky than just compounding as sanding removes paint and compounding removes paint.

It's not that it can't be done, it's just an advanced technique and there's a certain amount of risk that goes with it.

Even if you can sand and buff a factory paint job without going through anywhere, the paint will now be thinner than before and all the UV protection for the color coat is in the clear coat.

Again it's not that it can't be done as demonstrated here,

http://meguiarsonline.com/forums/showthread.php?t=30417

But for most people it's a fairly risky procedure to try to tackle yourself especially if you've never sanded and then compounded the sanding marks out using a rotary buffer.

Most all wet-sanding is done on fresh paint in body shop situations where the paint is softer to work on since it hasn't reached maximum hardness and because if the painter knows the car is to be sanded they will insure enough material is sprayed to give the guy doing the sanding and buffing work some margin to work with.

[pampos]

Re: Wet Sanding vs. Compounding Alone

If i am corrct it was a thread on another forum about what method remove more CC/PAINT.....It was a test between wet sanding/rotary/DA polisher....The results were surprised me as the DA removed more CC for full correction than wet sand and rotary...
I don't remember which one took longer,but i will try to find it and post it here.

[Mike Phillips]

Re: Wet Sanding vs. Compounding Alone

If i am corrct it was a thread on another forum about what method remove more CC/PAINT.....It was a test between wet sanding/rotary/DA polisher....The results were surprised me as the DA removed more CC for full correction than wet sand and rotary...
I don't remember which one took longer,but i will try to find it and post it here.

That was on Autopia.... not sure everyone agrees with the conclusion.

[pampos]

Re: Wet Sanding vs. Compounding Alone

That was on Autopia.... not sure everyone agrees with the conclusion.

That's why i didn't find it .I was searching on wrong forum

[10degreesbtdc]

Re: Wet Sanding vs. Compounding Alone

Here's pics of a test I did on my '85 S10 Blazer. I used a Mikrotest magnetic paint thickness gauge before and after. Since it's Pearl tri-coat the total thickness is high, but I don't know how much of it is clear coat. I didn't sand through so it's thick enough, I guess! Next time I'm going to measure thickness before / after wet sanding - before buffing - after buffing just to see although I might not be able to read the slight difference on this gauge that buffing makes.



Before wet sanding / buffing
Eastwood Liquid Ice / pad kit (wool, blue foam, white foam)
Paint thickness ~6.25 mil


After wet sanding / buffing
Eastwood Liquid Ice / pad kit (wool, blue foam, white foam)
Remaining paint thickness ~5.5 mil


What a difference! Probably still needs polishing/finishing, but won't know until my halogens and zenon spot light arrive. I'm really looking forward to getting my M105, M205 and trying that combo.

Total thickness change = -.75 mil. Is that average loss for wet sanding / buffing? Would that be excessive on factory paint/clear?