Author Topic: Painting these platic parts (Read 4409 times)

mycb750k6 · « **on:** July 18, 2010, 04:35:28 pm »

This morning a fellow here was having trouble getting his air box on his CB750. I noticed he'd painted it and it looked pretty nice. I'm surprised you can paint this plastic stuff and I'd much like to paint my plastic chain guard. he said he sand blasted it followed by spraying plastic adhesion promoter and then a coat of Duplicolor trim paint. Anyone had any luck in this area? I did read you can repair cracked and broken chain guards using a hot glue gun which actually works extremely well but is kind of an ugly patch. I'd like to paint over it if I could.

Toxic · « **Reply #1 on:** July 18, 2010, 05:23:37 pm »

I was the dumba$$ that couldn't get his airbox on.

I used the same procedure for the chainguard and headlight bucket.

You have to be careful with the sandblasting so that you get an even texture to the finish. Keep the nozzle the same distance from the plastic and it will give you a nice textured finish. The sandblasting gets you down to the raw plastic so the Adhesion Promoter can work

Duplicolor Adhesion promotor then the trim paint.

I find Duplicolor stuff is great but you have to follow the directions to the letter. Drying time - recoat time etc.

Don't use a primer.

I did all the plastic on my DRZ 400 supermoto and it's been several years and no problems. The DRZ plastic panels are real flexible and no cracking or pealing yet.

mycb750k6 · « **Reply #2 on:** July 18, 2010, 05:30:03 pm »

Thanks - I'll try it . Nobody called you a dumba$$. That's the way it goes sometimes and you would have probably figured it out yourself anyway. How far did you get on your 750?

Ichiban 4 · « **Reply #3 on:** July 19, 2010, 12:39:06 am »

Quote from: mycb750k6 on July 18, 2010, 04:35:28 pm

This morning a fellow here was having trouble getting his air box on his CB750. I noticed he'd painted it and it looked pretty nice. I'm surprised you can paint this plastic stuff and I'd much like to paint my plastic chain guard. he said he sand blasted it followed by spraying plastic adhesion promoter and then a coat of Duplicolor trim paint. Anyone had any luck in this area? I did read you can repair cracked and broken chain guards using a hot glue gun which actually works extremely well but is kind of an ugly patch. I'd like to paint over it if I could.

_________________________________________________________
I went through a similar situation with the chain guard on my 550K. The thing was cracked..tho not badly..but looked rough. Tried all kinds of things..here's what worked for me (and I'd challenge anyone to tell me it's been repaired/repainted..if they didn't know already).

Glued-up the cracks with Devcon GRIP-TON-ITE (Plastic super Glue)..part # 30350. Let dry/cure overnight>>sanded smooth (but left glue welt on inner surface/inside chain guard). Sanded & prepped whole piece..as for finish painting. THEN got a can of KRYLON "Fusion Superbond paint" for plastics. It HAS to be Fusion Superbond..the other paints just don't bond to the plastic like this does..and after it dries you cannot get it off without sanding off..as it becomes part of the surface of the plastic. Obviously..if the surface is smooth-uniform before painting..it looks like new plastic once the paint's on there.

You may get a lot of other opinions on what works best for painting plastic..but I guarantee that this works well..IF you use the exact products mentioned. It took me a couple of years of farting around with painting plastic on these old bikes..to get this one down.

Good luck!

Ichi

thehammer · « **Reply #4 on:** July 19, 2010, 07:22:08 am »

sandblasting not really necessary. I clean raw plastic with a green and yellow scotchbrite sponge and soapy water. then use plastic adhesion promoter. holds up on car bumpers.

The_Crippler · « **Reply #5 on:** July 19, 2010, 07:50:31 am »

Quote from: thehammer on July 19, 2010, 07:22:08 am

sandblasting not really necessary. I clean raw plastic with a green and yellow scotchbrite sponge and soapy water. then use plastic adhesion promoter. holds up on car bumpers.

Yeah, and I just lightly scuff up the finish with sandpaper - basically whatever you feel like doing to make the surface a bit rougher to grab the paint, and you're good to go.

mycb750k6 · « **Reply #6 on:** July 19, 2010, 08:00:26 am »

So the plastic adhesion promoter AND the Krylor fusion superbond plastic paint?

Ichiban 4 · « **Reply #7 on:** July 19, 2010, 11:59:10 pm »

Quote from: mycb750k6 on July 19, 2010, 08:00:26 am

So the plastic adhesion promoter AND the Krylon fusion superbond plastic paint?

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Can't speak for the "adhesion promoter" as haven't used it. Know that regular primer is not very good..in fact better to not use any sort of primer..I've found..as the paint seems to stick better.

This Fusion Superbond paint is completely different (and sounds like others posting here..either haven't used it..or don't know what it is). It apparently has some solvent properties that soften the plastic surface enough to get the paint to bond..but not really attack the plastic. By the time it's dry (to the touch in about 20 min..but needs to cure for about 24 hours to get to max hardness)..it's part of the plastic it seems.

Rather than banter about this though..why don't you get a can..try for yourself? It's only a few dollars..so what's to lose? Just remember though..that whatever the surface looks like before paint (cracks..scratches..etc.)..will be there afterwards.

Keep us posted.

Ichi

mycb750k6 · « **Reply #8 on:** July 20, 2010, 05:54:56 am »

OK I'll try it. Thing is, I've only got one 71 plastic chain guard and if I screw it up I'll have none and they are not available.
Fact it I did try this stuff in white last year on a polycarbonate gauge plate I made and it fish-eyed really badly but it was probably my technique. I don't paint so well. So if I screw it up, I'll put it on ebay. Isn't that what you do with junk you've screwed up with captions like "should clean up fine"?

Ichiban 4 · « **Reply #9 on:** July 21, 2010, 12:23:30 am »

Quote from: mycb750k6 on July 20, 2010, 05:54:56 am

OK I'll try it. Thing is, I've only got one 71 plastic chain guard and if I screw it up I'll have none and they are not available.
Fact it I did try this stuff in white last year on a polycarbonate gauge plate I made and it fish-eyed really badly but it was probably my technique. I don't paint so well. So if I screw it up, I'll put it on ebay. Isn't that what you do with junk you've screwed up with captions like "should clean up fine"?

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Shouldn't be a problem 750..can't be any further screwed up than now..right? The worst you can expect..is that you'll have to let dry/harden (wait 24hrs)..then sand down & start over.

Seriously though..if I hadn't been through all of this myself "been there done that"..actually worked it out..I wouldn't be recommending it so vociferously. The only real snag you might run into..is getting the product off the shelf @ local store. May have to look around a bit..or surf Krylon's Website..to find nearest dealer/seller.

Ichi

mycb750k6 · « **Reply #10 on:** July 21, 2010, 05:04:28 am »

No I actually found a can yesterday at ACE. I was looking for satin but settled for gloss black. When you sanded, what grit?

Ichiban 4 · « **Reply #11 on:** July 23, 2010, 12:53:08 am »

Quote from: mycb750k6 on July 21, 2010, 05:04:28 am

No I actually found a can yesterday at ACE. I was looking for satin but settled for gloss black. When you sanded, what grit?

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I used wet-or-dry #320..but if it has a lot of coarser scratches, nicks..you'll probably have to start out with say 150 grit (which can be dry)..and work on down to the 320. BTW: using wet sanding for the final step before painting..gives you a much smoother-finer finish.

I always use wet sandpaper for final sanding..before painting metal or plastic. Okay?

Ichi

mycb750k6 · « **Reply #12 on:** July 23, 2010, 06:05:54 am »

I did a test on an old rear inner fender yesterday after roughing it with dry 320. Actually I found the dry 320 too rough and the scratches too deep to cover but the finish was nice. I'm going to work my way down to 600 wet and try again. Is there a clear version of this stuff and can it be buffed when hard? I bought gloss black because they didn't have satin black but I'll stick with the gloss black I think.

Ichiban 4 · « **Reply #13 on:** July 23, 2010, 01:53:24 pm »

Several things come to mind..in reply to your questions.

1.) when using wet-or-dry sandpaper..it's always preferable to use it WET../because otherwise it loads up with dust/particles..and leaves a scratched surface..as you've observed (the water also carries away a lot of the dust..and actually helps burnish the surface you're sanding). I don't think it's necessary to go down to #600..which is extremely fine grit..and will load up and scratch the surface faster actually..if not used with water. When I worked in an auto body shop for a while..we always used a hose right alongside with the sanding to keep things flushed-away (turned-on VERY slowly though). You can also use a bucket and wet rags..which is only what most small jobs require.

2.) I don't know what other colors that the Fusion paint comes in. I used gloss black like you..and the finished results looked as good or better than new plastic. I remember seeing different colors in the store/on the shelf..maybe red..green..etc., but wasn't interested in them..so it didn't register. I don't remember seeing a clear..and besides that..would doubt that they would have it in this particular product..because of the nature of how it works (partially dissolving the surface of what it's sprayed on). It would seem that a clear would be counterproductive to what the paint is intended to do..form a finished bonded surface by itself.

3.) Regarding buffing..again..I think that that defeats the purpose of this type of paint..which is to leave a finished surface in itself.

All of this talk about clear coating and buffing..et al..reminds me of the differences in painting techniques over the past 25 years or so. In the past we never clear coated..but focused heavily on preparation and good quality paint..as well as spraying technique. Nowadays it seems like a lot of the attention to detail and technique has been lost..with the idea that whatever problems there are can be "covered" by clear coating. Not there there's anything wrong with clear coating I feel (sometimes it makes the difference between a good..and great paint job). But sometimes I feel it's used as an excuse to overlook the other preparatory details.

Anyway..to me..using this Fusion type paint..seems to get back to more of an old school approach to painting..which results in some really nice work..if done properly I feel..and especially when painting plastic..which is what brought-up all of this discussion in the first place..right?

Ichi

mycb750k6 · « **Reply #14 on:** July 23, 2010, 04:20:59 pm »

Thanks Ichiban 4,
What a great write-up. I'm excited about this now. I can't wait. I'll take some before/after pictures. The chain guard is cracked too so I do have to repair that properly first.

Ichiban 4 · « **Reply #15 on:** July 23, 2010, 06:35:51 pm »

You're welcome 750. Hope this works out well for you. I always feel that if someone has had to go through a hassle themselves..working something out..that it's good to share that with others..so they don't have to.

BTW: I noticed that we're both about the same age (I just had my 66th..as in "Route 66"..get it?). So I'm guessing that you have been exposed to a lot of the stuff I've been talking about..@ sometime in the past. Hopefully you can also appreciate that I'm not just BSing about my experience.

I also noticed that your Avatar is of Rocketman..from the late 1930's to post war years. I loved watching those movies..first in the theaters..later on Saturday morning TV. Thought that stuff was really "modern"..and would happen someday..which I guess in a technical sense has. Used to love watching Flash Gordon/Buster Crabbe too!

Later,

Ichi

mycb750k6 · « **Reply #16 on:** July 24, 2010, 04:38:41 am »

Yep, we're old, but wise

Not too many folks here can say they bought the CB750 when it first came out. Mine was a candy red 1971 K1. I think that's why I keep buying more K1s.

And Rocketman, aka Commander Cody, I was wondering if anyone would recognize him. Just twist a plastic button on your leather jacket and off you go. Yup weekly movie serials for twenty five cents to get in

On an unrelated topic, I have a post going with Johnie regarding trying to communicate with Yamiya to buy some of those kill buttons they just started making for their K0/K1 rt switches. Anyway your name just came up as someone who might be able to explain to them what we really want since we've struck out multiple times. Any truth to that?

Ichiban 4 · « **Reply #17 on:** July 24, 2010, 11:35:00 pm »

Hey..

I got Johnie's PM..posted my reply on the thread..about that. will need exact wording..for my wife to translate>>relate to Yamiya (she doesn't know anything about the technical details..hence the need to be very clear from the get-go).

Well..I hear what you're saying about having a first edition of the 750. I was just a poor college student..struggling to get by on the GI Bill @ the time..so couldn't afford one.

But did have a newish 450 twin..which was a demo..and more reasonable to get. That was a pretty peppy bike though..it really surprised me after it was broken-in. I wanted to get one of the new 500 fours when they came out also..but again..just couldn't afford it. Think part of my getting the 550 I have now..was part nostalgia for not being able to back in '72.

All this was in So. California @ the time..San Bernardino....not far from SJ Capistrano. Small world!

Ichi

mycb750k6 · « **Reply #18 on:** July 25, 2010, 04:38:58 pm »

OK here we go. here's my busted 71 chain guard with the old hot glue gun repair that didn't work.
SO I found the epoxy in the shop that says "some plastics". It's impregnated with steel filings.
Also I ran a 1" 2-56 stud through the two broken half's.

mycb750k6 · « **Reply #19 on:** July 25, 2010, 04:41:37 pm »

Here's the gunk and repair after the pin inserted. It's becomes malleable like play dough in about an hour so I'll go mess with it. Tomorrow I'll wet sand and paint it with the plastic paint. Wish me luck.

mycb750k6 · « **Reply #20 on:** July 26, 2010, 05:06:42 pm »

Finished guard.

Ichiban 4 · « **Reply #21 on:** July 27, 2010, 12:34:53 am »

Quote from: mycb750k6 on July 26, 2010, 05:06:42 pm

Finished guard.

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So..how do you like it 750 (BTW: do you have A "Real" name? Mine's Al).

It looks great to me. Mine looked the same. Can't tell it's not OEM when it's on the bike..I feel.

Al / Ichi

mycb750k6 · « **Reply #22 on:** July 27, 2010, 04:20:37 am »

At first I thought "it's really shiny" and then I looked at my red 71 and that one is shiny so it's supposed to be shiny. At least that one is and it's practically new. So I like it fine. Paint can says 7 days for chip resistance so I'll give it a couple before putting it back on and then take a final picture. I'm still not a painter but this does look 100% better than before. It doesn't look "painted". Thanks for your help. My name is Myles and I live in San Juan Capistrano, CA. The wet-dry 600 was perfect. It was a little rough getting through that epoxy stuff I put on there but the plastic cleaned up nice. It's just like anodizing. Whatever imperfections you leave on the part will be magnified once it's anodized. Same here, part had to be sanded smooth. This paint doesn't cover any mistakes.

mycb750k6 · « **Reply #23 on:** July 28, 2010, 10:24:37 am »

Looks nice - all done

Dunstall_74 · « **Reply #24 on:** July 28, 2010, 10:50:39 am »

Not trying to hijack this thread, but does anyone have experience with the Rust-Oleum Universal All-Surface spray paint? The can says it is good for wood, plastic, metal and masonry. I'm getting ready to paint my plastic side covers, and would prefer to only do it once

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Author Topic: Painting these platic parts (Read 4409 times)