Urethane Replica Wald Trunk Spoiler Paint not sticking
04-13-16, 10:43 PM
#1
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Urethane Replica Wald Trunk Spoiler Paint not sticking
I've searched these forums and google for a fair amount of time and am not finding my answer. Basically the paint wont stick to the bumper. I bought it from ebay FYI. Here are the steps I took. I've been testing the prep/paint on the inside of the bumper, havent doent he exterior side yet.
1. Washed the spoiler with Dawn dish soap and dried it thoroughly.
2. Sanded the spoiler with Scotch Brite scouring pads.
3. Wipe "plastic dust" with Isopropyl Alcohol.
4. Spray with Rustoleum Black Gloss.
This is where I run into the paint not sticking at all. I'm using light coats and its just beading up. Is it the paint I'm using? Do I need some sort of primer/undercoat?
Any help is greatly appreciated.
1. Washed the spoiler with Dawn dish soap and dried it thoroughly.
2. Sanded the spoiler with Scotch Brite scouring pads.
3. Wipe "plastic dust" with Isopropyl Alcohol.
4. Spray with Rustoleum Black Gloss.
This is where I run into the paint not sticking at all. I'm using light coats and its just beading up. Is it the paint I'm using? Do I need some sort of primer/undercoat?
Any help is greatly appreciated.
04-14-16, 12:50 AM
#2
Yes, you would need to use a primer. What you need to look for is a plastic primer. It's specifically made for urethane (or "plastic") parts and will be able handle the flexing/bending of the material. When body shops paint bumpers they use a special primer and clearcoat that has a "flex agent." This allows the urethane parts to naturally be flexible without causing the paint to spider or crack. Have you ever noticed some cars bumpers have cracked and peeling paint after a minor fender bender? That's usually because of poor or improper primer and clearcoat being used. Now that's not always the case, but is a good example. I hope this helps out.
04-14-16, 08:31 AM
#4
Sand it HEAVYILY with a Higher 280ish Grit paper first. Make sure you get all that nasty material off first. Then move on to a 380 Grit so smooth it out. Make sure there is no more top layer of that nasty Material.
Then you would move on to PAINT ADHESIVE.
Many people choose to skip this step but Idk why they would as it allows the coats of paint to PROPERLY adhere.
After that you would use a primer and paint as usual.
You should have no problems with paint not sticking as long as you sand and prep properly.
Gotta put in the extra work for getting cheaper materials.
Then you would move on to PAINT ADHESIVE.
Many people choose to skip this step but Idk why they would as it allows the coats of paint to PROPERLY adhere.
After that you would use a primer and paint as usual.
You should have no problems with paint not sticking as long as you sand and prep properly.
Gotta put in the extra work for getting cheaper materials.
04-14-16, 08:52 AM
#5
Rookie
Thread Starter
Yes, you would need to use a primer. What you need to look for is a plastic primer. It's specifically made for urethane (or "plastic") parts and will be able handle the flexing/bending of the material. When body shops paint bumpers they use a special primer and clearcoat that has a "flex agent." This allows the urethane parts to naturally be flexible without causing the paint to spider or crack. Have you ever noticed some cars bumpers have cracked and peeling paint after a minor fender bender? That's usually because of poor or improper primer and clearcoat being used. Now that's not always the case, but is a good example. I hope this helps out.
Sand it HEAVYILY with a Higher 280ish Grit paper first. Make sure you get all that nasty material off first. Then move on to a 380 Grit so smooth it out. Make sure there is no more top layer of that nasty Material.
Then you would move on to PAINT ADHESIVE.
Many people choose to skip this step but Idk why they would as it allows the coats of paint to PROPERLY adhere.
After that you would use a primer and paint as usual.
You should have no problems with paint not sticking as long as you sand and prep properly.
Gotta put in the extra work for getting cheaper materials.
Then you would move on to PAINT ADHESIVE.
Many people choose to skip this step but Idk why they would as it allows the coats of paint to PROPERLY adhere.
After that you would use a primer and paint as usual.
You should have no problems with paint not sticking as long as you sand and prep properly.
Gotta put in the extra work for getting cheaper materials.
04-14-16, 01:08 PM
#6
FYI, there is plastic-specific paints from Duplicolor that don't require primer. Used a satin black of this same paint on my cowl cover with excellent results!
04-14-16, 10:27 PM
#7
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Thread Starter
FYI, there is plastic-specific paints from Duplicolor that don't require primer. Used a satin black of this same paint on my cowl cover with excellent results!
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04-15-16, 12:32 AM
#8
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You are missing the the adhesion promoter followed by primer before painting. With raw plastic, it needs an adhesion promoter. Can use bulldog adhesion promoter. Pretty sure after that you can use 2k urethane primer. Just make sure it is compatible with the paint you are using.
04-15-16, 08:35 AM
#9
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You are missing the the adhesion promoter followed by primer before painting. With raw plastic, it needs an adhesion promoter. Can use bulldog adhesion promoter. Pretty sure after that you can use 2k urethane primer. Just make sure it is compatible with the paint you are using.
04-16-16, 10:19 AM
#11
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Supplies
A couple of lessons learned to share. The products for this project are listed below as shown in the picture from left to right. Also if my wald replica spoiler in the background looks warped that's because it is. I'm hoping that by the time I get it painted and mounted, it'll look straight. I tested all these on the inside of the spoiler to make sure I didnt make a mistake.
1. Klean Strip Stipper - poor choice, the raw urethane material absorbed this and became bubbly. Luckily I only sprayed a little to test it and was able to scuff it out. DO NOT USE.
2. Isopropyl Alcohol - I used this after I washed, scrubbed with Scotch Brite green pads. No issues here, good clean.
3. Bulldog Adhesion Promoter - Expensive and not for the novice. It came out splotchy and did not spray evenly. I finessed spraying this the best I could and I dont like it. So I bought the Dupli Color ad pro.
4. Duplicolor Adhesion Promoter - A third of the price and sprays and works fantastic.
5. SEM Primer Flexible Primer Surfacer - Havent used yet but it'll go over the AD PRO.
6. Rust Oleum High Performance Enamel Gloss Black - Sprays very fast and looks pretty good so far.
7. Rust Oleum Crystal Clear Enamel - I made the mistake and bought this...its NOT a clear coat. Ill have to buy the correct stuff.
1. Klean Strip Stipper - poor choice, the raw urethane material absorbed this and became bubbly. Luckily I only sprayed a little to test it and was able to scuff it out. DO NOT USE.
2. Isopropyl Alcohol - I used this after I washed, scrubbed with Scotch Brite green pads. No issues here, good clean.
3. Bulldog Adhesion Promoter - Expensive and not for the novice. It came out splotchy and did not spray evenly. I finessed spraying this the best I could and I dont like it. So I bought the Dupli Color ad pro.
4. Duplicolor Adhesion Promoter - A third of the price and sprays and works fantastic.
5. SEM Primer Flexible Primer Surfacer - Havent used yet but it'll go over the AD PRO.
6. Rust Oleum High Performance Enamel Gloss Black - Sprays very fast and looks pretty good so far.
7. Rust Oleum Crystal Clear Enamel - I made the mistake and bought this...its NOT a clear coat. Ill have to buy the correct stuff.
04-16-16, 08:13 PM
#12
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Thread Starter
Update
Heres an 'in progress' update while I wait for the paint to dry. Adhesion Promoter and Flexible Primer went on just fine. If anyone is watching, think its ok to wetsand the black gloss to remove the imperfections prior to clear coating without respraying another coat of black? I have sand paper all the way up to 3000grit. For some reason the paint came out ... bumpy. Its adhearing just fine to the primer...I think its the type of paint. Rust Oleum Black Gloss.
Edit: I just read that using anything greater than 600 grit is bad because its harder for paint to stick. Also wet sanding the base paint without repainting is a NO GO. I'll sand to clear up imperfections, paint using a different black, then clear coat.
Edit: I just read that using anything greater than 600 grit is bad because its harder for paint to stick. Also wet sanding the base paint without repainting is a NO GO. I'll sand to clear up imperfections, paint using a different black, then clear coat.
04-17-16, 07:50 AM
#13
You should only Wet sand the Clear coat. going from 1000 grit, to 1500 grit, ending in 2000 grit. Then you would want to use a cutting crème of some kind to even it out, and then you want to finish with a mirror like glaze polish on top. Both cutter and polish should be applied using a buffer with the proper buff pads for each respective application. How did you spray it on? It looks like it was sprayed on really heavily. As in you held the spray and moved slow.
If you want, you can look up proper paint spray techniques. You are supposed to go back and forth using light sprays to give it an even flat finish. It takes more effort and time but the end result is night and day.
If you want, you can look up proper paint spray techniques. You are supposed to go back and forth using light sprays to give it an even flat finish. It takes more effort and time but the end result is night and day.
04-17-16, 07:56 AM
#14
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Thats what is puzzling, I spent all day yesterday patiently spraying and waiting. Each coat was basically 'misted' on. I did not spray heavy at all. I sprayed evenly and lightly with even sweeps back and forth about 6-12 inches away. Project is over for now anyways, I wanted to start over so I stripped the paint with some harsh chemicals (that I said I wouldnt use) and now its warped to crap. Back to square one.
04-17-16, 08:29 AM
#15
It could be the paint then. My base paint comes on more like a flat finish. Very even and smooth. Try giving duplicolor a try. It sprays pretty nicely. Or you can use my source Paintscratch.com. They color match wel for OEM colors of any make or model. It just costs a tad more.
I spent all day sanding off the paint LOL. Took like 2 hours to sand everything off to its black base. I will be painting it today so Ill post my progress to give you an idea on how its supposed to look like after each stage.
I spent all day sanding off the paint LOL. Took like 2 hours to sand everything off to its black base. I will be painting it today so Ill post my progress to give you an idea on how its supposed to look like after each stage.