VHT Nightshades..(p0rk)

Ok well i bought a can of this stuff, and some 400 grit, 1000 grit, 2000 grit sand paper. First i sanded down with the 1000, then the 400, made sure there were no shiny spots, then i wiped it clean and hung it to paint, I put one light coat on it and while i walked away and came back(45 seconds) the paint looked like it was cracking? why is it doing this? i sanded it all back off and tried again and it is still doing it. any help appreciated. Thanks.

Did you clean it before you sanded?

There could be a wax or silicon layer that the sandpaper pushes around. Try cleaning with a solvent first.

^Like mineral spirits...pretty much lacquer thinner.

SickWitIt wrote:

^Like mineral spirits...pretty much lacquer thinner.

Depending on the grade/strength of the lacquer thinner,you can really make a mess on plastics. Prep-All or any alcohol based window cleaner works great too.



^^I use both.

Well the first problem is you sanded with 1000 then 400. You start with 400, THEN 1000. What lenses are you trying to spray? Some lenses ( namely the cheap Chinese plastic ) will NOT take to paint. I tried to both tint AND paint my taillights on my sport bikes and had the cracking effect every time. We even tried clear coating the plastic lenses first and then tinting over the top of the clear and got the same result. Cheap plastic is simply that, cheap.

SickWitIt wrote:

^Like mineral spirits...pretty much lacquer thinner.

Laquer thinner does absolutely nothing in terms of cleaning something correctly to be painted actually. Go to a local paint store and buy some wax and grease remover. USE IT PER THE INSTRUCTIONS(If not used properly it will cause more problems) But when used correctly it does its job.

I have not run into the problem that pork has with cheap plastic though. So that may be the case. I haven't done all that much tinting myself.

pOrk wrote:

Well the first problem is you sanded with 1000 then 400. You start with 400, THEN 1000.

Quoted for emphasis . You always start with the lowest number (corsest) sandpaper and work your way up to the highest number (finest) . Doing it in reverse may not be why the paint appears to be cracking, but it is definitely the wrong way to do it and will leave you with a 400-grit surface .

Ok, im doing it on my old pair of stock tail lights. one came out ok, one cracked really bad. I held my break knowing it may not work on my 3rd brake light and yep, didnt work. cracked. then i sand the 3rd brake light down again first starting with the wetsand 400, then 1000. Like you guys said. Then took a tack cloth from a local bodyshop(family friend) and cleaned off the surface. Sprayed a coat and let it tacky, then continued. Looks good after finished product. went back over it with duplicolor clear top coat.
What should i do now about the one cracked tailight. shouled i sand it all the way back down and try it again? or what. what will be the easiest way to take off the nightshade?

Picctures will come tommorrow of installed 3rd brake light.

If only one taillight cracked then its not the plastic, I would suggest sanding everything off with 400, then 600, then 1000 and getting a wax and grease remover and starting over. It should turn out fine.

BLAZER_97 wrote:

went back over it with duplicolor clear top coat.

Hmm...this could be a problem too. I do remember painting something a while back and cracking had occured because of the brand of clear I was using didn't match well with the brand of paint. I don't remember the actual brands that were giving me trouble though,but I know that when I used another brand of clear,it didn't crack.

try getting a paint to plastic adhesive and put it on the lense first...

I did a writeup on tinting my tails on here and can find it if you need.

^^Ill look for it.

I didnt use clear on the tailights yet, i used it on the 3rd brake light and it came out fine, as p0rk said im going back and sanding all off and retrying, i may use some plastic adhesive. As i said pics will come soon. Been kinda busy lately. Oh and the thread on the performance about my car missing and backfiring, was a crank sensor wire. Just got it out of the shop. 241$ to fix. And to find out i have both motor mounts broke and a ent/sagging transmission mount.