paint won't dry??

[Jake0147]

So, first off I'm working slowly on making a yellow bridge plate from a subdued one. I painted it with Plasti-Kote School Bus Yellow, on top of the matching and recommended plasti-kote primer. That was four weeks ago today...

Today I got back to it. I can touch the pieces just fine. If I touch them together, they bond instantly and a layer of paint transferrs from one to the other. If I set a clean and dry spray paint can on one, for about ten minutes it leaves a small imprint around where the can was, and some traces of yellow on the can but does not do so instantly. It is too "mushy" to sand back off effectively, but it does come off somewhat with acetone. What remains after that seems "properly dry" and will sand off reasonably well... I wish I knew better how to describe exactly the state that this paint is in...

What gives? I'd like to blame it on bad paint, but understand I am not a painter and am learning as I go. I have successfully used spray paint before however. This was not that old (I believe) as none of the mixing balls were stuck (I look for that when I by spraybombs) and all was shaken well beyond the recommended amount. Is there anything I could have possibly done wrong to cause this? is this what "bad batches of paint" act like? Would you consider it safe to replace the paint with another can of the same from another lot? I do like the color for this, otherwise I'd simply try again with another brand...

Thanks in advance.

 

[m.walker]

Bake it next time , if you have no oven to use try a holagen work lamp close enough to keep it warm .

 

[dentman]

just a guess, but how thick are you applying? try and lay it down in many thin layers with several minutes flash time in between coats. also if you can get it into an hvlp gun you can buy a product called "rocket it" or rocket.... its a super fast hardener bumper repair guys use at dealeerships. takes a 2 hour clear coat down to about 15 minutes. HTH

 

[Jake0147]

I'm semi-confident that it wasn't on too thick, three coats, five minutes apart (roughly) from different angles, the "before" color did not dissapear completely until the third coat. Primer and color were applied this way. I've surely gotten spray paint too thick before, and the runs and drips were very very dry after a day, let alone four weeks... This is the reason I am questioning the paint, otherwise I would surely question myself exclusively...

I don't know about hardeners and accelerators and such... This is spraybomb stuff. I was hoping to avoid turning this simple and non-authentic thing into a big project... If I've got to buy mixed paint for the sprayer, then so be it. Gillespie 24087 dried in the same environment. (Not at the same time, that was last sprayed the weekend before I started this, and it's very well vented...) I tried that stuff straight from the can (bad call on my part), with slow reducer (bad call on my part), with fast reducer and hardener (overcompensation on my part) and with fast reducer only in it, which in the end came out like I feel it should. The worst case scenario there (slow reducer and too much of it) took a day and a half to dry to the touch and a week before I felt I could handle it, but it all dried eventually...

Here's what I'm thinking-
I'm going to put the light directly on a couple of the plates that I havn't messed with yet.
I'm going to find another can of the same paint, and paint a couple of more plates and put them under the light.
I'm going to paint a couple of plates again and leave them to dry unassisted, as I feel spraypaint should be able to dry this way, no?

That should tell me what I have to do in order to proceed. (further suggestions welcome on that). The can of paint it's self is nothing really, it's just that I am still mystified as to how it could fail to dry for this long in the first place??? Even misapplied, or mis-manufacturered, It boggles me. And worries me for future applications where a failure is not so relatively insignifigant.

 

[Armada]

Did you put the primer on bare metal or over top of existing paint? Sounds like the plasti-kote is reacting to the old paint.

 

[wb1895]

If you are attempting to spray paint over CARC I would imagine that the spray paint and CARC are not working too well together. CARC is designed to resist chemical coatings. In my limited painting experence, sand it all the way to bare metal and spray on a nice layer of primer and let sit for several hours. Once the primer is dry then apply the base coat.

If you cant sand all the way down to bare material then get a good high dollar primer and start from there.

 

[GoHot229]

If you are attempting to spray paint over CARC I would imagine that the spray paint and CARC are not working too well together. CARC is designed to resist chemical coatings. In my limited painting experence, sand it all the way to bare metal and spray on a nice layer of primer and let sit for several hours. Once the primer is dry then apply the base coat.

If you cant sand all the way down to bare material then get a good high dollar primer and start from there.

You may infact be right about the CARC 'shedding', however I'v went to 'Wallys' anf gotten the camo spray cans and had zero problem with anything, other than wishing I had a case or two of the stuff. Possably the cans were mixed wrong at the factory with the hardening agent not added in the mixing process???? At any rate I'v had good adhesion with spray can camo over CARC.

 

[Armada]

At any rate I'v had good adhesion with spray can camo over CARC.

All coatings are not created equal. Some will work, some will not.

 

[Jake0147]

Did you put the primer on bare metal or over top of existing paint? Sounds like the plasti-kote is reacting to the old paint.

I would have said that properly dried (cured) paint was inert..... It can really do this?
The numbers were sanded down enough to find anywhere from two to six old numbers underneath the ones that were on it. When metal started showing I stopped sanding... Perhaps leading to the specific areas that would not wipe away with solvent...
This makes sense. More experimentation is in order.

And no I do not know if it is CARC or not. The finish looks different from the CARC that I have seen, so I'm thinking not, but it's not that different, and may have simply been sprayed in a better environment than the wheels I'm comparing to...

 

[Jake0147]

Ok, to close this thread I have some results-

First, the non-dried paint IS over pre-existing green, the bare metal sections are the part that would not wipe away with acetone... (In my mind,) The compatibility issue is confirmed.

Second, I have one single test number plate that I sanded to BARE metal all around. There was enough in the original can to do one side, and a new can to do the other side. Both sides dried enough to handle in ten minutes, and after one day seem fully dried. (In my mind) The previous diagnosis is verified a second time.

Third, nothing including paint stripper will touch the green paint remaining on the number plates. I'm adjusting my opinion, and I'm leaning towards it being real deal CARC paint. This further confuses me, because it would seem that this should be as un-reactive as anything, and make a good base for new paint. That's kind of why I left most of it on there when I got down to the last layer, not because tit was CARC in particular, but because it was good tough paint, and stuck very very well to the aluminum, I figured "it's a good base".... The Rustoleum rusty metal primer that I used on the wheels I've done so far, that stuck to the CARC on those wheels like crazy glue, it worked out really well.

Live and learn I guess... Thank you all for pointing me in the right direction.