hecklerkoch

Not sure where the best place to post this question but I have limited time at this terminal so just posting here. I have recently painted a frame using (non-catalyzed) single component paint (acrylic enamel). Now here is my question: Can I paint over this type of paint using a 2 part polyurethane clear (catalyzed) ?

I have attempted to research this online with little success it seems everyone has a differing opinion on whether or not it will work. The paint store employee told me that it will probably be ok if the single component paint is given a long enough time to cure it might not be dissolved by the activated paint and ruined. Does anyone know for sure? The brand of paint used was Duplicolor and it is the common blue metallic color.

Dr.Deltron

From what I've read here, Duplicolor is laquer. In which case catalysed clear should be OK.
If, as you say, it's acrylic enamel, then I'm not sure.

Best bet would be to do a test tube on some PVC plumbing pipe.

DO let us know the results, please!~

repechage

Duplicolor is from my use laquer, smells like Laq., comes off with laquer thinner...

vpiuva

One non-professional's experience. Dr D's critique is welcome.

background: I had painted two frames with Sherwin-Williams catalyzed clear over cat enamel and it worked perfectly. Did take a little longer to really get hard like I wanted, but that's another issue, and it's great now.

Then I needed to paint another frame - SW did not have the gold I wanted, so I went with a Valspar single stage acrylic enamel from another store. Guy selling me the paint said go ahead and use my leftover SW cat clear over it, no problem.

Result - as soon as the clear hit the frame it was running like water. Maybe I was doing something else wrong, maybe I mismeasured, maybe the temperature was wrong. I don't have a good answer. The clear hardened just fine and had zero effect on the base coat, but I ended up with runs all over. You only see them close up, so I haven't pulled out the fine grit paper yet. But someday.

Dr.Deltron

I would tend to agree. Acrylic enamel is, as far as I know, a laquer based product, unlike regular enamel like Testors or One-Shot, which is mineral spirits based. Sooo...

DO NOT spray any laquer based paint over mineral spirits based paint!!!

Vice versa IS doable though.

Sounds like the clear was over reduced. In other words, too thin.
Either that, and less likely, is that you had the flow knob way too far open. In other words, too much paint coming out.
Temperature was probably NOT the culprit.

A better fix than all the time, trouble and falderal of sanding with fine grit & polishing, (seeing as you have multiple runs) is to sand with 320 grit and carefully reshoot a coat or two of clear.
I know that sounds kind of bass ackwards, but the time is about the same and the results are MUCH better! (IMHO)

I just saw a nice new Lexus drive by me the other day, and as it passed, I couldn't help but notice the entire car was covered in sand scratch swirls!
Instead of making the car look shinier, it looked like crap!

Again, a sample tube of PVC is your friend!
Better a 25 cent piece of plastic than your beloved bike frame!

Grand Bois

Duplicolor says "acrylic lacquer" on the can. That's why it's easy to use and doesn't hold up.

Dr. Deltron does great work, even if he can't spell lacquer and he thinks acrylic enamel is lacquer based.

dbakl

Enamel and lacquer are 2 different things.

hecklerkoch

Okay the can does not say either way Im not sure why I assumed it was acrylic enamel. However it does say that it contains toulene so I assume thats the main solvent used. Definetely not mineral spirits based so hopefully it will be okay. I will do some tests on another surface before applying the clear. I am used this paint on both my bicycle and my ct70 frame. Dont have any pics of the bike but here is the ct70.

repechage

Test, don't guess I would agree, but PVC for "testing".?... you probably did not mention that priming it first is required, (no?) for test sprayouts I use some smooth cheap steel tube that comes along, more of an apples to apples comparison, same base layers as the work has. Long long ago I used the fork, easier to do a complete rework on a fork than a frame.

Recently I did some lug lining tests for a frame, I noted that the different brands of paint pens reacted differently with the 2 part clear, one stayed bright, the other went dull, test do not guess. Thank goodness bike frames do not need much paint.

brew

Is there a rattle can type paint that will hold up better than duplicolor? i was thinking of possibly painting my old beater mountain bike for a winter bike. The frame is not worth anything but i want to clean up the surface rust and spray it so i dont have to ride my specialized in all the stupid salt.
I have heard of custom mixed automotive paint they can put in to a spray can if you dont have paint guns. Would that stuff work better than duplicolor?

vpiuva

I've seen my local paint store do this but they have a 10 (?) can minimum order. I remember per can it was pretty reasonable, but with the minimum order size it was much more expensive than buying the small amount of paint I needed for a bike.

Grand Bois

It might be cheaper to buy a used gun and rent a compressor. I paid $40 for my Sharpe MGF HVLP detail gun.

bbattle

Krylon with clear coat over it and some good car wax over that. Several light coats, sand between coats. Make sure everything dries completely. Periodic waxing will keep your frame happy and shiny.

duane041

If you want durability, you want a catalyzed color (requires a hardener). Anything that will be put in a spray can will be mixed with more "drier" additive (PPG uses one for their acrylic enamel so that it can be used as a brush touch-up). This drier is all that will make the paint dry. There will be no crosslinking of the paint and the hardener, because if they were to add the hardener into the spray can, you'd have a 16 oz. block of color the exact same shape as the can.

For durability, engine enamels work well, but dry very slowly, especially without heat (a heat gun would help in this area). Otherwise, use a good etch primer before you go to the Duplicolor, and thhen follow with a good catalyzed clearcoat.

Oh, and temp could have affected your problem with runs, but usually it's cold weather that does that. An improper temp reducer will have a direct effect on how quickly (or slowly) your paint and/or clear will set up. I'm sure Dr Del will tell you that using a "slow" reducer like DT885 in the fall is just asking for it

McDave

I've been very pleased with Rust-oleum's Metallic paints. They dry much quicker than the old Rust-oleum stuff does and have held up very well on my kite buggy, which gets much more abuse, including salt water, than my bikes do. Read the directions on the can and use their primer and clear coat sprays too for best results.

Here's an example photo. Sorry I don't have a good closeup showing the metallic flakes (need to do that one of these days).

dbakl

In my experience, a 2-part paint will go over most anything, as its catalyst, not solvent based.

Grand Bois

So there are no solvents in 2-part paint? That's not what my Material Safety Data Sheet says.

hecklerkoch

Just to update on this I did finally paint the clear over the restoleum metallic. Went on with no problems and did not affect the color coats. I did have some orange peel occur but that was do to my very poor quality spray gun. I am happy with how it came out and I will post up a pic or two soon.