by "Jake - Has Bad Luck So You Don't Have To" (murdersofa)
Published 05/30/2017 at 23:28
by "Jake - Has Bad Luck So You Don't Have To" (murdersofa)
Published 05/30/2017 at 23:28
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STARS: 1
Plus - my bumper matches now. Minus, despite using adhesion promoter, primer, then paint and clear coat, and giving it a few days to cure a slight brush with a pressure washer took a chunk of paint off of my lip. Don’t get why paint won’t stick to the damn thing. Other minus: I didn’t notice until after I laid down my color base coat that somehow there were still a ton of sanding marks in the paint that didn’t show up after several coats of filler primer and block sanding that somehow didn’t get rid of them. Fuck it. Close enough for now. I give up on this fucking shit. It would have looked goddamn amazing the first time I tried this shit if I was actually given paint that matched.
Looks alright from a few feet away.
It’s hard to capture on camera but the finish has a mottled finish to it from the sanding marks and some uneven places. So damned annoying. I also have to still clean off the dry clearcoat overspray (where the particles dry before they hit the surface and form a white haze) somehow, probably with acetone and a paper towel. I dunno what to do with this damn lip though. I’ve done everything I can think of to make paint stick to it but it continues to defy me. I cleaned it off with acetone to remove any residue from the manufacturing process and scuffed it up with a 120 grit sanding sponge thing and some 600 grit paper to give it texture for the paint to bite into. Still not sticking. Ugh.
"Frank Grimes" (FrankGrimes)
05/30/2017 at 23:34, STARS: 1
Next time try scrubbing the bumper with TSP. But if its an old bumper instead of a fresh new bumper it probably is something else causing the paint to fail. Did the paint have a flex additive?
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/30/2017 at 23:36, STARS: 0
The lip is where the paint is failing. Yes, the paint has a flex additive. I told the paint shop I was using it on urethane parts and they tailored it accordingly. Does TSP have some sort of specific effectiveness over acetone and engine degreaser?
"Svend" (svend)
05/30/2017 at 23:43, STARS: 2
Did you give it a good wipe down with isopropyl alcohol before painting?
To be honest unless the paint was cured using an infrared heat lamp I wouldn’t touch it with a pressure washer for a good four weeks, open end hose and car shampoo, no chemicals (ie tar remover, etc...) in that time, even baked in an automotive oven I’d still be cautious. It may seem cured to work with after 24-48 hours, but under the surface it can still be take a while to cure and gas off.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/30/2017 at 23:47, STARS: 0
engine degreaser and then acetone. Thing is the paint on the bumper has been adhering fantastically, but the lip is just shrugging it off.
"Frank Grimes" (FrankGrimes)
05/30/2017 at 23:49, STARS: 0
engine degreaser I think has oils in it I would never use it on something to paint. TSP is just a very harsh soap that on a new plastic part or bumper will really get it clean of all mold release silicone or any of the solvents oils and crap that could come out of new plastic.
Acetone wax and grease remover lacquer thinner or I have been told even glass cleaner are all that I would use on something to clean before primer or paint.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/30/2017 at 23:57, STARS: 0
Hmm. I’m not sure if this degreaser had oil or not. It was some sickly smelling red industrial strength stuff.
"Frank Grimes" (FrankGrimes)
05/31/2017 at 00:16, STARS: 0
I dont know for certain it has oil in it but the industrial type degreaser crap i’ve used leaves behind a greasy smelly film to stuff and seems like it needs another solvent to get it off.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/31/2017 at 00:17, STARS: 0
Oh, yeah this stuff doesn’t leave behind a film. Huh.
"themanwithsauce - has as many vehicles as job titles" (themanwithsauce)
05/31/2017 at 00:22, STARS: 1
Chemistry answer - TSP stands for “Tri sodium phosphate”. It is a detergent/surfactant while degreasers are solvents. TSP will chemically attack the oils and greases while the solvent will “dissolve” them but only if the solvent can properly encapsulate the oil and grease. WHen you’re dealing with that lip, that plastic has been exposed to a LOT of road grime and whatnot over the decades. There is dirt and grease so far embedded into it that the solvents can’t quite remove the embedded stuff. TSP will be a bit more thorough at getting out whatever is in there that you can’t even see.
......But be warned - TSP plays hell with aquatic life. Be kind to the local waterways and do NOT dump it down the sewers willy nilly. Use only what you need.
"Svend" (svend)
05/31/2017 at 01:53, STARS: 0
Could the acetone be reacting with the plastic of the lip (is it the same plastic as the bumper?), I know some plastics don’t behave too well with certain chemicals where they are fine with others.
"LeftOfTheDial" (leftofthedial)
05/31/2017 at 08:08, STARS: 0
What paint did you use and where’d you get it? Not trying to help, this is for me.
"Monkey B" (monkeyb)
05/31/2017 at 10:42, STARS: 0
A) Don’t use that type of degreaser, it leaves a residue and is likely the reason those hazy looking spots appear the way they do. It’s hard to tell from these photos but those spots look like contamination causing “fisheye”. Use a proper prep solvent, acetone is not strong a good enough wax and grease remover.
I’m not sure what products you are using so it’s hard to help on your adhesion issue. Is the adhesion problem area a new part that came in raw plastic form or was it primed or painted previously?
I’d remove it, strip everything you’ve done to it, prep it and find someone to spray it for you. I’d bet you could find someone to do it for a few hundred or so if it’s off the car and prepped properly.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/31/2017 at 11:25, STARS: 0
The lip is a new part that came unpainted. The hazy spots aren’t fisheyes, they’re sanding marks that I somehow didn’t see when I primered it (possibly because the lighting in my dad’s garage is garbage). My issue is I can’t figure out how to strip the bumper all the way down. Even using chemical paint strippers can’t get through the OEM paint layer very well and led to the current uneven as shit result, so I’d need to find someone to strip and prep it as well as paint it which sounds like $$$$$$$
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/31/2017 at 11:26, STARS: 0
Custom mixed aerosol from a local auto paint supplier that a lot of body shops in the area get their paint from.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/31/2017 at 11:26, STARS: 0
I’m really not sure.
"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
05/31/2017 at 11:27, STARS: 0
The lip is brand new, actually.
"Monkey B" (monkeyb)
05/31/2017 at 16:03, STARS: 1
those sand scratches are standing out because they are most likely loaded with contaminants, and while they don’t look like your normal fisheye the result is due to the same. If you used a standard purple degreaser than the residue is probably trapped in said sand scratches and acetone wasn’t enough to rid you of them due to fast flash time.
After typing that I reread what you did, never use anything more aggressive than 220 on plastic bumpers. What you could be seeing is the roughed up plastic that occurs when you use something to aggressive and don’t follow up gradually. Usually 220/320 then 400 wet is a good bet.
Hard to tell from photo’s, could be either of the first 2 paragraphs giving you the result.
you can find paint stripper specifically for plastic bumpers. SEM and Klean-Strip both offer it in an aerosol IIRC. Give the areas you painted a quick scuff with 220, it’ll allow the stripper to get in there and work faster and you may be able to just take the area you sprayed back to OEM coating before it cuts through it as it’s really not that aggressive. It’ll also work more quickly in the sun. Wear rubber gloves, shit burns.
The spoiler may strip just by trying to peel it off or hitting it with an air tip. You may need a specialized primer for the raw plastic more robust than the standard adhesion promoter. Another thing you’ll want to do after getting it to raw plastic is leave it in the sun on a hot day so it opens up and releases as much mold release from the material. Wash with dawn dish soap then wipe with a wax and grease remover...always wipe that stuff on and follow with a clean rag for assurance of removal. Wet sand with 400 then continue as advised with whatever products you use. We used to put raw plastic parts in the booth while the oven was cooking a fresh job to get the mold release agents out before prepping. We also didn’t leave those parts in for baking after paint...pulling them out when tack free so as to avoid additional issues with mold release. Once the paint cures a few days it’s a good bet adhesion will take.