what am I doing wrong when wet sanding orange peel?

[sys202]

So I have been trying to paint some plastic headlight covers and a grille. I have made multiple attempts to paint them with a hvlp spray gun and also 2k single stage rattle can paint. When I go to wet-sand the orange peel out or buff it using meguiar compound/polish and buffer pads, it seems like by the time I work out the orange peel I am getting burn through every time now matter how careful I am. Grey "primer" specks start to show through. I understand that their are more high/low's and edges that need to be avoided, versus working with large flat panels. Is this a result of not applying enough coats of paint? Rather its 2 stage clear coat, or 2k single stage aerosol paint?

[DasBurninator]

Re: what am I doing wrong when wet sanding orange peel?

Sounds like you have a couple things going on.

First, I am guessing that paint is sprayed thin. Single stage is generally a touch softer as well depending on the pigment used. You may also have some high spots (the specks you see coming through) in the primer prior to laying down the paint itself.

Second, 2000 grit paper is a bit aggressive. See what you can do with 2500 or 3000.

What compound and pads are you using?

[sys202]

Re: what am I doing wrong when wet sanding orange peel?

Thanks for the reply.

So here is what I think my issue has been. 1) as you mentioned thin layers, I think I was avoiding doing a lot of wet coats in fear of getting runs. 2) I was using 1500-2000 grit, but I will use a 3000 grit. This last time over the weekend I resprayed the parts and applied a lot more heavy/wet coats and the orange peel is very very minimal now 3) I have been using the meguiar hand drill DA pads compound/polish:

https://www.amazon.com/Meguiars-G3507-Compound-Power-Pads/dp/B009OBVXC0

https://www.amazon.com/Meguiars-G3500-Power-System-Tool/dp/B009OBVRY4/ref=pd_bxgy_263_img_2?_encoding=UTF8&pd_rd_i=B009OBVRY4&pd_rd_r=JP9XX997JEFH4C21KSAF&pd_rd_w=k0uTy&pd_rd_wg=Tf4Fm&psc=1&refRID=JP9XX997JEFH4C21KSAF

This time I am going to do a light 3000 grit wet sand and skip the compound buffing completely and just polish it with an actual variable speed polisher w/ wool pad and machine polish.


P.S. I was wondering, when buffing/polishing parts that are this small like grilles and headlight covers, is a bench style polishing machine more ideal over a variable speed polisher?

[DasBurninator]

Re: what am I doing wrong when wet sanding orange peel?

The hand drill DA stuff isn't the best suited to what you are doing.

As a rule of thumb, never wet sand what you cannot reach with a pad. Sometimes the best option isn't wet sanding at all. Nicer paints like Sikkens help make that possible.

There are tools out there for getting into very tight spots. They are pricey though.

http://www.autogeek.net/rupes-ibrid-nano-long-neck.html

[sys202]

Re: what am I doing wrong when wet sanding orange peel?

Thanks a lot for the info man!

[greg0303]

Re: what am I doing wrong when wet sanding orange peel?

I echo what was mentioned above: try less aggressive sand paper. You will have a better control and of course it will be easier later to remove the sanding marks.
If you wet-sand by hand inspect the area after every 4-6 strokes. Soak the sand paper for at least 15-20 minutes, before use, and use plenty of water during the process.

[DasBurninator]

Re: what am I doing wrong when wet sanding orange peel?

I echo what was mentioned above: try less aggressive sand paper. You will have a better control and of course it will be easier later to remove the sanding marks.
If you wet-sand by hand inspect the area after every 4-6 strokes. Soak the sand paper for at least 15-20 minutes, before use, and use plenty of water during the process.

To expand on this a bit as well:

Water with a drop or so of dishsoap, or I mix up some D114 that I use for wet sanding.
If I could have a friend sitting there with the spray bottle and spraying the section while I sand, I would do that.

Also don't fold the paper, cut it into smaller pieces if you need. If the paper creases, toss it out.
The sharp edges will cause deeper sanding marks.

When possible use a sanding block as it helps produce even pressure. Or on larger areas a DA works even better and takes off less paint than doing things by hand.

[sys202]

Re: what am I doing wrong when wet sanding orange peel?

One more follow up question. Could you further explain what you mean by "As a rule of thumb, never wet sand what you cannot reach with a pad."

[DasBurninator]

Re: what am I doing wrong when wet sanding orange peel?

One more follow up question. Could you further explain what you mean by "As a rule of thumb, never wet sand what you cannot reach with a pad."

You should never wet sand where you cannot reasonably access with a buffing pad/buffer. An example of this would be a recessed area on a bumper where you cannot physically get a pad.