Mcleod

Question For The Automotive Topcoat Users

14 posts in this topic

Have a question regarding the use of primers or adhesion promotors, namely, do you use them? and if so do you mind sharing the process which you use?

I've been testing some Dupont ChromaClear lately with mixed results. Most Suprising to me, baits without adhesion promotor performed much better than those with it. At this stage I have used both Dupont and third part plastic adhesion promotors with both Createx and Automotive paints. I have attached a couple of pictures, the first two show the result from "knifing" with the adhesion promotor while the third without any adhesion promotor shows virtually no lifting.DSC_3551.jpgDSC_3553.jpgDSC_3554.jpg

With all the baits, performing rock smash tests, things held up well during the high speed impact, it was only when they were knifed that the above occured. Initially I thought the problem might have been the Createx not sticking to the adhesion promotor, however, when I tried the automotive paint I was very suprised that it did the same thing.

Any information of assistance apprieciated.

Angus

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Did you scuff the plastic before painting? I never use adhesion promotor on plastic baits, knock the shine off the plastic with scotch brite pad or sand with 400 grit, never a problem as you have experienced. I use automotive basecoat / urethane clearcoat.

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Did you scuff the plastic before painting? I never use adhesion promotor on plastic baits, knock the shine off the plastic with scotch brite pad or sand with 400 grit, never a problem as you have experienced. I use automotive basecoat / urethane clearcoat.

KcDano,

Yes sorry missed that detail, all of the bait's were scuffed, cleaned and degreased before application of adhesion promotor. I dont know the equivalent grit for the scuff pad I used, however, the shin was certainly taken off and the bait well scuffed.

Thanks for the feedback

Angus

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Angus,

If you performed the following respectively: "were scuffed, cleaned and degreased "

You might try degreasing first before sanding on some occasions you can drive a contaminant into the substrate surface by sanding or scuffing which will have detrimental impact on the finish, such as you have experienced. I would simply try it without the adhesion promotor and see if the problem arises again and go from there.

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I did not see a mention of priming the baits. I use adhesion promoter on my baits and recently on large Muskie sized plastics on repaints. My lures are wood ,dipped in propionate (plastic) and I scuff with 320 and I spray one light coat of the adhesion promoter and then I prime with two part automotive epoxy primer sealer, urethane paints and two part automotive clear. From my friends who are in the bump business

and the directions on the adhesion promoter it appears to be for using before priming on plastic parts or over areas that are already painted for adhesion and blending out spot repairs. I only used the primer on plastic repaints and my baits and they held up great. When I ran my baits (Propionate over wood) in to a Michigan cold November I noticed on some the paint egg shelled or wrinkled a little on the lures belly and a couple on the lures nose. After checking it out I found that it lifted off of the Propionate primer and all. I believe the Propionate contracted and expanded at a diiferant rate than the wood and paint. Last season same drill and no failures using the adhesion promoter. In all fairness I did not scuff the propionate before priming the first season because I was told the Primer Sealer being an acetate base would self etch to the Propionate. The propionate looked like the day it was dipped where it lifted. I can not comment on water based paints other than I would not use them with the adhesion promoter or clear because the automotive urethanes are part of a system designed to work together. I spray the primer out of an Paasche H model with the large tip I believe #5 with no more than 10% reducer. If you are spraying in a higher temps I would go to the slow reducer for everything if it seems like it is drying to quick, that could create an adhesion problem.

I spray the Chroma Clear that was given to me a few years back. My activator went bad and when I tried to buy the activator for replacement I was told it was off the market for a while. Is it back on the market or is yours older as well? The paint supplier told me the hardners were the same and I bought an aftermarket hardner that worked fine. watch the safety cap on your hardener mine was not screwing down tight. Hope this is helpful David

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I recall reading an article on the HOK forum about Bulldog adhesion promoter, with input from the guy who writes the HOK tech sheets.

I believe he suggested that there is a time window to apply the basecoat after the adhesion promoter has been applied, and that the adhesion promoter must be applied VERY THINLY.......and if I remember correctly, he sprays the Bulldog onto the plastic part and actually wipes it off - that's how thin the coat needs to be.

I was led to believe from the article that if the above wasn't done accordingly, that the adhesion promoter would actually be detrimental to adhesion.

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Thanks all for the feedback and info, I will try the suggestions and let you know how it goes. I think there is merit in all of them so got some more testing to do!!!!!!!!!!!!

Dan, I'll try changing the sequence and see how it goes.

Fishthanks,

No mention of primer because I havent used one. If I dont have to I dont want to use one because it saves on another step in the process. If it ends up I do then so be it. I have a 2pack primer that I can try, however, it is not transparent. Any primer I use I would like to be transparent and allow the paint to define the colors. I'll look into it though. With regards the hardner, I am using the medium temp one because Dupont advised that would be best for me, and I dont know whether it is too old or not. It was a brand new can which I got from them so I assume it is ok, I dont want to buy one though until last resort to save cost. With regards the paints, the problem occurred with both createx and automotive paint so I dont think that is it at the moment. Given that the topcoat and paint peeled I am assuming at this stage that it is ok. I'll do some more test though and see.

Stringjam,

You might have hit the nail on the head with the time window for paint application. I spoke with dupont rep today and he mirrored your comments so that will be first port of call to test.

Thanks again to all, apprieciate it. I'll let you know how it goes.

Angus

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When I paint or repaint plastic lures, I dip or brush them in acetone to insure a clean surface. I get good bonding of paint, in my case Createx or AutoAire, and never have any paint failure.

I started doing this because I wanted to repaint some jerkbaits in a ghost finish, and needed to get back to clear plastic before I started. The acetone is a solvent for the plastic, so I am repainting onto a "virgin" plastic surface. I don't soak the lures, just dip, or brush, and let drip dry, which is really quick, so the lure integrity is never threatened.

It's a quick, cheap technique that is probably worth a try before you get too deep into different bonders and primers.

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Thanks all for the feedback and info, I will try the suggestions and let you know how it goes. I think there is merit in all of them so got some more testing to do!!!!!!!!!!!!

Dan, I'll try changing the sequence and see how it goes.

Fishthanks,

No mention of primer because I havent used one. If I dont have to I dont want to use one because it saves on another step in the process. If it ends up I do then so be it. I have a 2pack primer that I can try, however, it is not transparent. Any primer I use I would like to be transparent and allow the paint to define the colors. I'll look into it though. With regards the hardner, I am using the medium temp one because Dupont advised that would be best for me, and I dont know whether it is too old or not. It was a brand new can which I got from them so I assume it is ok, I dont want to buy one though until last resort to save cost. With regards the paints, the problem occurred with both createx and automotive paint so I dont think that is it at the moment. Given that the topcoat and paint peeled I am assuming at this stage that it is ok. I'll do some more test though and see.

Stringjam,

You might have hit the nail on the head with the time window for paint application. I spoke with dupont rep today and he mirrored your comments so that will be first port of call to test.

Thanks again to all, apprieciate it. I'll let you know how it goes.

Angus

Angus, I have not seen any adhesion promoters that were designed for water based paint. I paint quite a few baits for Toothy Muskies and I can not imagine not using primer. Primer in itself is for adhesion and for the paint itself to adhere to. It should not affect color at all when you are covering it with a base color for the begining of your painting process anyway. Skipping a step in the process will give you less than stellar results, If the first layer fails they all fail. There is a time window for painting or priming after applying adhesion promoter, if you exceed that time you are supposed to put on another coat before coating. I was lucky to have an experienced auto body friend who made and painted thousands of baits shorten my learning curve. good luck and have fun.

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I make all my lures out of cedar but I have painted a lot of plastic lures for people and have never had any problem with automotive paint adhering to the plastic. I still mainly use lacquer but have also been using some urethanes. If its a new plastic unpainted lure you should be able to paint right on the lure. If its one that is painted allready i usually lightly scuff the paint with sandpaper that I think is 400 grit. then pour a little lacquer thinner on a rag and do a quick clean off with it. I have never had any issue with paint not sticking. After painting I clear coat with a 2 part urethane clear. (Make sure your wearing a good respirator and have good ventilation)

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Mark, Thanks I will give that a try

Fishthanks,

I havent tried it yet but I am going to test the time window after application of adhesion promotor and I recon it is definately one of the issues. With regards the primer, it is more important for me to get it right so if it is needed so be it, I intend on doing a few test bait's with it aswell. My only issue with the primer is it influences my ability to make ghost baits because I cant find a clear primer, I can only find a clear adhesion promotor, hence this is why my testing has been done with it thus far. final product quality is more important though so I will be trying the primer. At the moment I dont have enough experience with water based paints on adhesion promotors but I will take your advise on-board and do some further testing. Because the automotive paint is not working either I will sort that problem first and then move onto the next.

Leo,

Sounds simliar to Mark, a bit of acetone and paint away, I'll give it a go.

Thanks to all, got some more testing to do and we will see where it ends up. I will let you know how it goes.

Angus

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Read the side of the can it will give you the wait times and if you wait too long you are to scuff sand before refinish in most cases. Follow these directions as spraying to quick or waiting too long both causes problems. On hard surfaces like a lurer I would scuff with a red scuff pad spray the base and clear. Sometimes putting too much paint on is worse than less as you will come more to chip. The bumpers are flexable and the type of plastic they are have to use a promotor so it will stick. The hard plastic on a lurer the paint should bite with out it. Cub48

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I've only painted a few "ghost baits" so I'm no expert, but all I did was spray the Createx colors right onto the bare plastic. No primer and no adhesion promoter. I did thoroughly wash the baits in dish washing liquid with water as hot as I could stand it and then rinsed them in straight hot water out of the tap. After drying I lightly scuffed them with 400 grit sandpaper and then painted as normal. The scuff marks went away after painting and top coating. So far there have been no problems.

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Just an update on my adhesion problems, I have tried a few baits and things are looking up. It is just early days, however, the baits are definately holding up better in the backyard tests following changes to the process. Here's what I changed,

1. All test baits were cleaned and degreased both before and after scuffing. I honestly dont know whether this had an impact or not, however, in my eye's it can only be a positive.

2. Adhesion promotor thickness was reduced. Instead of a couple of coats, I applied one thin coat.

3. Reduced the time window for application of paint following adhesion promotor. I dropped it down to 10 minutes following application of the adhesion promotor

4. Tried a 2 pack primer which I had lying around.

The end result was a definate improvement in adhesion to the plastic bait. During "rock" testing the bait's definately held up better and when I attacked them with a knife the paint did not come up like it did previously. Hopefully that problem is well on its way to being put to bed.

A couple of observations / theories, I actually think the baits with the adhesion promotor held up better than those with the primer. They both appeared to survive the rock tests in a similar fasion, however, when under the knife, the paint appears to not stick as well to the primer as it does the adhesion promotor. I dont know whether this is a result of water based paints and primer adhesion or whether because the adhesion promotor and topcoat are from the same company and gelled well together, who knows.

Next step is some field testing and I am going to try whether adhesion promotor then primer then paint is an improvement again. Who knows but will be interesting to see. It would be good to be able to stick with the createx paint but in the end the result is more important than the process for me. If it doesn't come up trumps I might try some autoair before heading back to the solvent paints.

Thankyou to all who replied and assisted me with this problem, hopefully the feedback above can assist others or even yourselves in the future.

Angus

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