Getting Towards the End... Need Help With REAL Wetsanding:

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Getting Towards the End... Need Help With REAL Wetsanding:

Post by LV2DRFT on March 23rd 2012, 8:21 pm

So I made it through about 10 coats with quick wetsanding, and using the low grit levels made the paint come off pretty easily. I never went for zero orange peel before, but called it good after knocking most of it off. Well it became obviously harder and harder to do with each step up in grit.... and then my wife got jealous and scratched my paint half way through, so I had to put some thick dabs over her marks which turned out to be pretty hard to sand flush with the rest of the paint... although I think I've got them pretty good now.

Anyways the question is:

How do I know when to finish wetsanding towards the end of the job when I'm now wetsanding with 1200 grit paper? My plan is to do a GOOD wetsand with 1200 then put on two more *careful* light coats then wetsand 1500 up to 3000 and polish to finish the job.

The reason I'm asking is because I just went crazy on this (and still see gloss spots) for about 10 minutes on a small section as pictured here--

-- and it still doesn't seem like it's "ready" even though I'm literally taking certain spots down to the original paint because I'm hitting it so hard... this is after TEN coats of buildup! I've heard that you can say "enough" when you can no longer see gloss spots and all of it is uniformly hazy. It's kind of hard to tell in the picture but all the dark spots pictured are glossy. So I don't know if I should stop here in order to keep from removing all ten of my previous coats because I'm getting crazy with wetsanding, or if what I'm showing in the picture is good enough... I'm thinking possibly I shouldn't worry about killing the gloss spots because I can see the "layer ripple" or whatever you call it around rougher spots. So I'd assume that means the transition is very gradual and might not be a big enough deal to keep knocking off more paint.. at least that's what you're supposed to be looking for when doing bondo I believe.. I'd appreciate a little help from someone who's gone through this and finished the job on their own project.

Thanks!!!
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Re: Getting Towards the End... Need Help With REAL Wetsanding:

Post by LV2DRFT on March 26th 2012, 2:17 pm

I just did a little polish test... you really do need to get an even hazy look for it to polish up without blotches. 1200 isn't strong enough to get through multiple layers of bad sanding. I read (after it was too late) somewhere else on this forum that orange peel compounds itself after every coat. Very true haha. I believe my only solution is to sand it all with 600 again and start from there to get it even... and this time I'll get an even hazy look before rolling the next coat.
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polish test

Post by gazza01 on April 8th 2012, 2:08 am

i had terrible trouble when sanding down. I used my bonnet as my practice panel to see what kind of finish could be acheived.
At that point i wasn't sure that i would use the roll on method or not, but thought i woul clown d give it my best shot.
I drove myself nuts trying for perfection. It seemed every time i tried to get the final coat totally flat, i would suddenly get a little patch
which would burn through. This patch would also be a different shade of the colour being painted on.
I spoke to a guy at rustoleum who has been working with this paint and others for 30 yrs who told me that you must let each coat harden properly (more than touch dry) at least 24 hrs of heat over 20 degrees, and that was a real minimum, otherwise you are trapping the previous coat which can then take forever to dry. He also told me not to bother with 100% flattening but to stop at
around 80%, then once flattened, leave it to dry again for at least a day or 2, then try a good polish, and that i may find that although the surface is not 100% flat it may look that way when polished and buffed.
I didn't really believe him as having worked with cellulose in the past i would always 100% flatten in order to get that mirror finish.
However, i thought what the hell, and did as he said and hey presto, the finish is glassy and i coudn't believe that no orange peel
was showing through at all. Give it a try.
Also you mentioned paint bubbles still in the paint. That sounds to me that your mixture may be a little thick.
Just over 50% paint should do the trick. I go for 60% paint now as it still flows well and lets out the chemicals from the white spirits and air, so no bubbles. Also make sure you pre mix your paint and keep it in a container as this made my finish a whole lot better (not sure why). Patience, a good eye, and letting the sandpaper do the work, is the key. Good luck and keep the faith.
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Re: Getting Towards the End... Need Help With REAL Wetsanding:

Post by LV2DRFT on April 10th 2012, 2:25 pm

gazza, thanks for the help and advice. It will keep me going as I work and work :-)

I just gave in and bought some more 220 grit paper as I needed it to smooth out some bondo areas that actually weren't as smooth as I'd originally thought. Once the 220 lost it's "cutting power" I saved the used sheets, put them on a kitchen sponge and gently sanded the other parts that still had shine spots. That seemed to do the trick!

I also block sanded most of the flat areas of the car that showed body work flaws when I had a new coat of gloss on it, and wow, what a surprise! Turns out there were LOTS of uneven areas under the paint, not because of the orange peel, but because I just didn't see them until getting that gloss black on. When I block sanded with 220, I took some areas around these minor indentations down to bare metal.

So it seems my problem was partially that the metal underneath wasn't 100% smooth, and partially that I needed to sand more orange peel / was being lazy with my prior sandings. Anyway I decided to go all out since I'd already exposed some original paint, and smooth it out quite a bit... hopefully that should help as I build up coats yet again. Learned a lot though and hey I didn't even waste much money on my paint because it's rustoleum (cheaper than spray primer by volume haha). I now fully understand the need to buy tons of primer and use the shadow to find peaks and valleys when doing bondo though :-) I guess I just did it the hard way but since I used all my budget money I'm not too disappointed. I just get another chance to put 6 more coats on with a smoother base (and get to spend 25 more hours "appreciating my hard work" yaaay!)

Anyways enough blabbing--

Here's what I'd like anyone else reading this in the future to learn:

IF you are happy with your finish (i.e. the imperfections, dings and body work feathering is good enough for you to be happy with), make sure to sand your last few coats with a sponge covered with sandpaper. It helps to make the sanding a little more flexible :-)
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