Auto paint touch-up spray question...

[pfbz]

I wanted some color-matched spray paint do paint some trim pieces on my Ford truck (color code UJ, Sterling Gray metallic).

None of the big autoparts store brands (like duplicolor) had the correct color code, so I had a local auto paint shop custom mix the color and put it in some spray cans for me.

I degreased the plastic parts I was painting, scuffed, put on adhesion promoter, and then several thin coats of the color coat. I didn't have any clear coat at the time, so I decided to let it dry and put on the clear coat later. Three days later, it is still a bit tacky and soft! Dry, warm weather.

I've painted several trim pieces in the past with off-the-shelf rattle cans with pretty good results, so it's not like it is my first time spraying with a spray can, but it is my first time using a two-stage paint.

Did the paint guys mix the paint wrong, perhaps not putting in enough hardener? Or is it simply the nature of two-stage paints that they will not dry to a hard finish without a clear coat top layer?

Help a newbie with auto-paints out!

 

[GStaz]

Did you mist on the adhesion promoter or hammer it on thick? Adhesion promoter can be a great help, but can cause a failure if used too heavy. It is possible that the store mixed the paint incorrectly and that's why it is not drying. You could try to force-dry it in a last ditch effort. Either use a heat gun and run it back and forth over the parts for a while at a distance of about 8"-10" or set the parts out in direct sunlight for an afternoon. If they still aren't dry, it's a lost cause and you'll have to refinish your parts.

 

[kirk.g]

You dont put hardener in the base coat only the clear.Base coats I have seen dry in minutes at room temp.I dont think you can blend a finish very well with spray bomb.More so the older the paint or vehicle is.There is car paint forum out there somewhere.....You could probably buy a small inexpensive compressor and touch up gun for not much more than they are charging you for custom made spray bombs......just my 2 cents worth

 

[ZRX61]

You dont put hardener in the base coat only the clear.

Every basecoat I've ever used has required a catalyst..

 

[HVAC Phil]

Every basecoat I've ever used has required a catalyst..

Alot of basecoats use a hardener as an option, unless it is single stage, then it's required.

 

[countryroad82]

Every basecoat I've ever used has required a catalyst..

Dupont Chromabase doesn't require it, nor does Sherwin Williams Ultra 7000. Duponts Nason brand shows that it is required, but I never use it, I like to keep my leftovers for coloring in other projects so I don't use as much paint. To the OP it sounds to me like your adhesion promoter may be reacting to your base, as stated before it may have been layed on too thick, or it just might not work with the brand you are using. I have had that happen before myself, that is why I am bad to stick to one brand of paint products. I use the same brand primers, adhesion promotors, flex additive, sealer, base, clear, whatever chemicals that go into the finish, which I also use the same brand body fillers, in my case USC. Sometimes I may use the lesser priced brand from the same company (like Duponts' Nason line) but only after I have tested it myself for extended periods of time.

 

[Piper]

not to move you from GJ as the advice and knowledge here is excellent but specific paint questions are always addressed here http://www.autobodystore.com in the forums section. Excellent site.

 

[pfbz]

Thanks for the input!

I used two very light adhesion promoter coats, and it seemed to flash dry without any problem, but I hadn't even considered it as a source fo the failure... I also left the parts in the direct sun for several hours on day two to try and get it to harden, but no luck.

I think these particular parts that I tried painting are done for as the finish is starting to get blemished every time I handle them to see if they are dry. Not the end of the world, but I really wanted to know if it was my process or the paint itself that caused the failure.

But just to make sure I understand two-stage paints... Whether or not the base coat "requires" a catalyst, the base coat itself should dry to a hard finish even without a clear coat on top?

 

[kirk.g]

hmmm? so are you saying that you put hardener in both?

 

[Zeke]

You mentioned plastic parts. Take some spray and do a metal piece and see if if hardens.

 

[countryroad82]

The base paint will be dry yes, but as of it being "hard" like enamel not really, it will have a sort of rough texture to it but it will still be sort of soft if that makes sense. It won't come off on your hand or anything but you can certainly scratch it with your fingernail. The clear is what gives the protection from the elements and such and the hard, slick surface.

 

[kirk.g]

Also if plastic is part of the bumpers or anywhere that is collision absorbing then you should use flex agent.Or the first time you bump up against something the paint will crack.