enamel clear coat still "sticky" after days

[dellamorte]

i painted a few enclosures and have let it  dry in front of a heater between coats and after a few days,(one is more than a week) the cleat coat is hard but still "sticky" to the touch.
im wondering if it is because of cheap/old clearcoat ? i would think the clear would be cured after a few days in front of a heater. i dont want to go buy a toaster oven to bake them if its not gonna make a difference.

[ianmgull]

I'm not quite sure if this applies to you but... After I bake a clear coat it is usually still sticky for a day or two after I take it out. Only after it's been heated and then left to dry on it's own do I get a hard coat. I'm using the cheap wal-mart stuff too.

[dxm1]

Right - try moving it away from the heater. Let it air dry for a day (covered, if it it sticky).

[dellamorte]

the 1st one i sprayed has been away from the heater for probably a week and its still tacky, not in the way that the paint isnt dry , its more like if you hold it in your hand for 30 secs it sticks to your skin

[dxm1]

Most enamels (and some acrylics) take at least a week to fully "cure". They should not feel tacky after about 24 hours, though. Is it very cold or humid where you are at?

[GREEN FUZ]

I had this problem once. I think it`s to do with the relative humidity in the atmosphere at the time of spraying. In other words, try to pick a nice dry day when painting.

It will eventually dry but there is a distinct possibility of it been covered in impressions of your fingertips from repeated attempts to test if it`s dry yet. 

[zombiwoof]

Can't you just use a regular oven to bake it?  I don't think you need a toaster oven.
My apologies if you don't own a normal oven!

Alan

[foxfire]

Can't you just use a regular oven to bake it?  I don't think you need a toaster oven.
My apologies if you don't own a normal oven!

Alan

yes, you can use an oven as long as you don't ever plan on cooking food in it ever again. same goes for the toaster oven.

[cpnyc23]

I've had something similar happen and the only variable that I could pinpoint was humidity.

Above 75% humidity and you are destined for stickiness.   72 degrees and dry air is the ideal... so if you live on East Coast you've got about 13 hours a year of prime atmosphere.

Maybe I could drill a bunch of enclosures, fly to Hawaii, paint and clear coat them and then send them back to Brooklyn... yeah, that's it! 

-chris

[m-theory]

The things that affect paint drying:

1.  Film thickness and dry time between coats
2.  air movement
3.  temperature
4.  humidity

I'd say that, if your clear coat is "hard" but still tacky, it's because you've trapped a lot of solvent underneath the film, and it hasn't worked its way out yet.  Be careful with it.  The finish is extremely vulnerable in this state. I'd let it just sit and air dry somewhere for a few days and see what happens.  It should tighten up when you get it away from the heat.  The heat is only turning those solvents underneath the film into goo at this point.  They need time and air movement to work their way out.  If you apply more heat at this point, you risk solvent popping, because the surface has skinned over, but the solvents underneath still want to get out.  Force them out too quickly and they'll leave holes in the finish as they escape. 

Btw, single stage paints never really "cure."  Not to be the word police, but the term "cure" is usually used to refer to the chemical process that occurs when a hardening agent reacts with the resins in the paint to create a new material that is impervious to solvent re-wetting.  Single stage paints are always re-wettable, regardless of how long it's been since they were applied.  You can take a bit of thinner on a rag and dissolve any finish that's not been catalyzed, regardless of how dry or hard it may be.  It's the nature of the beast. 

[cpnyc23]

m-theory...

how does one then catalyze the paint on a pedal?

-chris

[BubbaKahuna]

One other thing to consider:
Some paints that have frozen over the winter and thawed are now junk and will never dry right.
If that's the case, strip it and start again with fresh paint.

Cheers,
- JJ

[dellamorte]

i think it might be an old can or the humidity, for now im using future floor polish and going to buff it out with micro fine sandpaper

[m-theory]

how does one then catalyze the paint on a pedal?

There's really little need to.  Hardened finishes are used for their chemical resistance, UV and other weather resistance, and chip resistance, all of which contribute significantly to durability and longevity.  The only characteristic that would matter to a guitar pedal is chip resistance, and that would be completely negated by the fact that there is no flex to the substrate and not enough primer to provide any cushion effect.  At the end of the day, they're going to get chipped, regardless of what kind of finish is used. 

[alanlan]

I had a similar problem with some urethane potting compound (the 2 part stuff) which just would not go off, no matter how accurately I tried to mix it.  I guess acrylic is a completely different material though is it?  I'm not very hot on material science.