[ptcamaro]

Is it ok to wet sand 2K? I think it is but is'nt it absorbing water.
Anyway I dry sand the 2K with 220 then 400 dry. Should I sand anymore or Can I epoxy seal it as it is?
Thanks guys.

[baddbob]

You can wetsand any 2K. If you're using a sealer 400 dry is usually fine for the final sanding. 400 wet may be too coarse though. Bob

[rrmccabe]

Its OK to wetsand.

In my opinion 400 is a little course for final sand. You might get away with 400 but 600 is a safer bet.

Sometimes slight metalics like silver will show sand marks with 400 so I like to finish with 600.

I also like to sand my epoxy with 600 before painting so you might want to do it then. This is one final step to make sure you have everything right.

As I said it depends what you are painting with. Base/Clear? Single Stage ? What color?

Rich

[rrmccabe]

Originally Posted by baddbob

You can wetsand any 2K. If you're using a sealer 400 dry is usually fine for the final sanding. 400 wet may be too coarse though. Bob

Bob, you get more sandscratches wet than dry? Seems the opposite to me??

Rich

[Bee4Me]

For me,it's both.
Summer-wet
Winter-dry
I hate funking up my shop with dry residue but I'm not crazy about sanding wet when it's 40*outside either. Then you have the mess inside when doing wet in the winter. It's just easier to blow it out the door than clean it up from wet sanding.
It also depends on the vehicle I'm doing as well. one's that are sealed well and can be dried good vs. open this & that for water to hide everywhere.
I prefer 600 wet followed by a double stack gray scotch pad dry.
badbob recommended this to me and has proved very successful in eliminating any missed scratch's from paper. That and a close inspection when using grease & wax remover on the final cleaning.
I also allow a day or two to dry out depending on temp.

[mrcleanr6]

i usually dry with 400 then spray a coat or two of 2k sealer. without the sealer 400 will be too coarse for metallics as mentioned before. wet is ok but too sloppy for me, i'm a gray dust kind of guy. if you go for the 600 then i think wet is better since it will clog quite fast and take forever.

[kenseth17]

Hmm I've been sanding 400 wet and haven't seen any sand scratches, haven't sprayed a silver lately though. I often knock down the base a little with 1000 once its covered and spray another coat. I wetsanded a 68 cougar a long time ago with 600 wet on k200 and it seemed to take a long time sanding and the paint just seemed not to be as chip resistant as when I started using a courser grit. I feel as course as you can go and still cover the scratches is the best. Just my 2 cents for what thats worth. I don't use k200 anymore though. But most tech sheets say 500-600 wet for basecoat metallics. 400 wet is equivelent to around 320 dry in terms of cut I believe.

[rrmccabe]

Originally Posted by kenseth17

Hmm I've been sanding 400 wet and haven't seen any sand scratches, haven't sprayed a silver lately though. I often knock down the base a little with 1000 once its covered and spray another coat. I wetsanded a 68 cougar a long time ago with 600 wet on k200 and it seemed to take a long time sanding and the paint just seemed not to be as chip resistant as when I started using a courser grit. I feel as course as you can go and still cover the scratches is the best. Just my 2 cents for what thats worth. I don't use k200 anymore though. But most tech sheets say 500-600 wet for basecoat metallics. 400 wet is equivelent to around 320 dry in terms of cut I believe.

I think most the time 400 is fine but like I said I have seen silver metalic base follow sand lines (for lack of a better term). I have seen this on several occasions.

I am amazed. I always thought dry left more scratches grit for grit. I admit it really feels smooth but it seemed to leave more occasional dry bigger scratches. Maybe from dry caking. I don't know. Will take you guys word for it.


Rich

[kenseth17]

Okay, straight from the notes I took 15 years ago in tech school
Operation DA Wet Dry
Featheredge 80-180 NO 80-180
Final sand
Lacquer 240 400 320
Urethane 320 500-600 400
Primer
1st NO 240 180
2nd NO 320 240
3rd No 400 320
Color sand No 1000-2000 No
Plastic filler NO NO 36,80,100

But this was 15 years ago. The paints seemed to have more fill then to me. The paint today seems to be a bit thinner, and some of the newer more vibrant colors seem to be tougher to cover, probably due to a lot of toners in them. And who uses lacquer anymore. One thing I noticed from working in production shops though years ago, is if final sand with 320 on a da and don't seal, you may see little swirlys from the da with some colors. I like to final sand wet myself. I just feel it does a better job, paper goes a longer way, and it to me seems to do a better job for covering with paint although the grit comparison seems to say different, Use whatever works for you. Wetsanding is messy though, and cleaning up all the sanding sludge bites sometimes. Hopefully the tech instructor gave the right info, and I was paying attention and took proper notes. Ohh and it says not to sand primer with a da, if you work in a production shop, ha ha, there goes that theory.

[baddbob]

Originally Posted by rrmccabe

Bob, you get more sandscratches wet than dry? Seems the opposite to me??

Rich

People argue wetsand vs drysanding all the time, some people prefer the dust to the sludge, some say dry is faster and others will say wet is faster. We all know it can be done both ways so it's more of a personal preference than anything. But I have to say, wetsanding is definately more aggresive than dry sanding and this can also be supported by what most paint manufacturer's recomend for their prefered final sanding grit. You'll notice many suggest 400 dry or 500 wet and the reason for the different grits is because the wetsanding cuts are deeper. So can we assume if the same grit papers are used will the wet cut faster if it cuts deeper? I would think so.

For years all of my final sanding was done with 400wet then 3M changed how they graded their abrasives (1990) and it started cutting more like 320 showing scratches on metalic jobs and people were complaining. Since then we've had to change to finer grits for prep especially on metalics. My preferred grit is 600 followed by a rubdown with a grey scotchbrite but sometimes I use 800 depending on the mood I guess because I really don't see much of any difference in results. If you're spraying a sealer 400 dry (hand sanding)would be about the coarsest grade I would consider using especially with metalics, 400 wet may be too aggresive IMO, 400 on a DA is usually alright.

Currently I switch back and forth between wetsanding and drysanding with grits between 220 to 400 but for anything finer it's always wet.

3M's trizac system for colorsanding dry is misleading IMO, I watched a demonstration video when it first came out and they stated that it's been proven that drysanding is faster than wet but IMO unless they do a side by side demo in front of me to prove me wrong I'll put my money on wetsanding being faster with the finer grits. 3M wants to sell sandpaper and the system is great for most in that they can easily track how the progress is going without having to dry the panel and also less mess, but wetsanding is faster. Load two sanders up one with dry and one with a wet paper and see for yourself.

That's just my take on wet or dry, I'm sure some will disagree. We all get our work done one way or another Bob

[ptcamaro]

Allots of opinion, guys helping me or confusing me lol. 400 dry sounds like good enough from the info you guys gave.
I'm going to use BC/CC from SPI. Color is torch red by the way.
Thanks as always.

[kenseth17]

Yeah, those dang painters on here. You'd think years of sniffing fumes and chemicals, (and possibly drinking too) would kill some brain cells and they wouldn't get so analytical over a simple topic, but that doesn't seem to be the case on this board. Hope you are not too confused now. 400 dry sounds good to me. Hope all goes well for you.

[baddbob]

, yeah, sorry. torch red:400 dry then sealer and spray away

[ptcamaro]

Kenseth,
I was worried 400 dry being coarse allso but after reading 400 dry being not rough than 400 wet (Bec I allways tought wet sanding smoother) my mind now at peace.

[rrmccabe]

Kenseth17 what do you mean PROBABLY drinking?

Bob, I agree wet cuts faster. I guess that makes it more agressive. I think dry gets the low spots caked and the grit does not penetrate as deep. At least thats the way it seems to me. But, the wet seems to be more consistant for abrasion. Like every part of the sandpaper is doing the same work because it is continually cleaned.

As I mentioned earlier, dry in the same grit feels smoother. I dont know if its the powder on it that makes it feel this way or it really is. But it seems to me the dry is not consistant across the paper. It may be smoother on 95% of it but the other 5% is worse.

I really dont know for sure. I just found it interesting your comment and thought I would comment.

My biggest battle is not knowing what I can get away with. I know I do way too much prep work because I am not sure if it will cover. Takes me forever to do anything but when the color goes down, its always right

I too dry and wet sand. Depending on the panel and details. Both have their place.

Rich