More decal questions...

[mattpocket]

So, I've been experimenting with decals as you know (one experiment left the photocopier at work needing a new fuser!)

Anyway, I sprayed a box up in a green metallic paint, got my decals, coated them with clear, and let them dry (well, actually I put the whole sheet in the microwave oven! Which worked rather well!)

Anyway, I put a decal on the painted box and it looked great, really cool...

Then I put a coat of clear over the top... and the decal is now about ten shades lighter than the box!? I am guessing this is due to the metallic paint (which often changes colour with clearcoat)... is there a way to prevent this?!

Matt

[ezanker]

You could try putting a couple of coats of clearcoat over the paint before applying the decals.  Then a couple more over the decal.

NOTE: I have not tried this myself, so cannot vouch for it...
EZ

[mattpocket]

Mmmm... it seems to have cleared up a bit, when I checked it earlier on, seems to be better since it dried, but then I managed to lock the keys in the garage, and I dont have a spare set until my parents get back from france on fri/saturday, so my box is locked in until then! 

[mattpocket]

Do you think it would be possible to use laser decal paper in an inkjet printer? Would the clearcoat cause problems afterwards? Just a thought, I will try it anyway...

Matt

[MikeH]

Try getting yourself a can of clear gloss polyurethane spray.  You'll have to bake it to make it smooth, but it works really well on darker colors.  Not so great on bright whites though.

Ps- I have locked my keys in the garage painting enclosures at least 3 times. Grrrr!!!! I just end up taking the door off of the hinges.

[mattpocket]

Try getting yourself a can of clear gloss polyurethane spray.  You'll have to bake it to make it smooth, but it works really well on darker colors.  Not so great on bright whites though.

Is there a difference between polyurethane and the clear lacquer they use for car bodies (which is what I am using)

Ours opens upwards (I dont know what the average garage door looks like in the states) and the hinges are on the inside...

Matt

[MikeH]

Clear coat for car paint is usually enamel.  I've never had good results with that stuff.  If you don't put it on at the right time, or it's too heavy, it eats off the damn label and the paint too.  Polyurethane is different stuff, and it wont eat plastics the way enamel will.

[modsquad]

Having been a model builder in my past (airbrush and all...).  I will tell you that the rule of thumb is never coat over any paint with a paint that is "hotter" than the underlying paint.  Now what does that have to do with decals you ask.  Well if you print on an inkjet chances are that if you use enamel over coat it eats the darn thing.  So here is the order of paints from coolest to hottest as far as chemically.

The volatile portion of the paint mix is what dissolves and disperses the skin (what's left behind) forming ingredients.

The volatile solvent used in enamels is usually one of the following:
Turpentine
Mineral spirits
Benzol, Toluol, Xylol and Naptha

The volatile solvents used in lacquers is usually one of the following:
Acetone
Ethyl Acetate
Ethyl Alcohol
Butyl Acetate
Toluol
Butanol

The solvents used in Acrylics is usually one of the following:
Isopropyl alcohol

Lacquer adheres via a chemical bond that etches itself into the surface. On the other hand, enamel and urethane bond to the surface.


What this means is, lacquer paints can have enamel and acrylics applied over it, enamels can have acrylics applied over it but not lacquer, and acrylics can have nothing applied over them. Conversely you can't apply lacquer over enamels or acrylics. Acrylics over Enamel over Lacquer. When you think about it, it makes sense - lacquer solvents can melt enamels or acrylics, but enamel solvents can't melt lacquer based carriers/pigments, and acrylic solvents can't melt enamel or lacquer carriers/pigments. 

This goes for clear coats.  So moral of the story is the nasty stuff dries really quickly but will eat anything under it that's not of the same ilk.  I use an acrylic clear coat that looks milky when applied so you think its causing discoloration.  But when it dries it dries clear.

[mattpocket]

Right, for my next load of questions...

Does that mean I shouldnt coat my decals in this stuff to begin with!? haha Cos I gave a whole sheet a real thick coat of clear laquer on wednesday, and to be honest, it looks like its holding up pretty well! haha I put green tinted metallic, then a decal, then the clear, and then locked the keys in the garage, so I cant tell you what the finished article looked like, but the sheet of decals that I covered in clear seem to be bearing up ok! haha

Is tinted car paint (i.e. the green metallic stuff I used) ok to use under the clearcoat car paint?

I read the other day that painted aluminium chips really easily unless you use an etch primer? Which costs double what normal primer does, is this a necessity? How much will it help. Could I use some old FeCl to etch the surface of the box before I spray a normal primer, to help it adere? Seems like a cheaper option, just a thought?

Matt

[modsquad]

I use etching auto primer on the boxes and it seems to be tough as nails.  I have not really found a paint yet that doesn't chip.  The main issue is that the paints that are really "hard" and durable are not really good on stuff that gets knocked around.  Now I just bought a can of the stuff they paint appliences with that I am going to try.  I would think it would be tough as nails.  However, it only comes in white.

As far as decals, when I was modeling I always sprayed lacquer clear coat over the decals and seemed to be fine.  It really depends on how they were printed.  I would think a laser printer would be fine to lacquer over.