Gloss Paint and Sanding

"rattle" or spray cans can give an acceptable finish. Get a gloss Italian red, shake it up real nice, let it sit in a bath of hot tap water for about five minutes. Then you're ready to spray; do a light mist coat, let that dry for about thirty minutes and follow with medium cover coats thirty minutes apart till you get the depth you want. hth

The Keeper (of too much crap)

You know, I never did quite understand the purpose of this. They didn't explain it in the tutorials. ;) Can anyone explain this to me?

The hot water helps the paint liquify and flow real well. The little bb in the cans should be shaken for at least a minute before painting. I usually wind up giving it five minutes before initial use. Four minutes before each subsequent coat, give it a hot bath and a shake. hth

The Keeper (of too much crap)

Hot paint well mixed is thinner and the propelant is at a higher presure than cold paint. (Don't ever use boiling water unless you want to paint your ceiling when the can explosively ruptures.

Back in the 50's, an uncle of mine (with low IQ) put an "empty" Reddi Whip can in his incinerator. He was lucky he didn't burn the neighborhood down when the can blew out the side of the incinerator. Be careful heating the paint. No hotter than hot tap water.

The light mist is indended to produce smaller paint droplets. The mist on the model does not tend to "blob" up and produce an orage peel.

On the other hand, all well polished cars (1:1 scale) are color sanded and polished to get rid of the surface ripple. This includes the two stage jobs, where the clear coat is "color" sanded and polished. Color sanding is done with very dry paint, fine paper and water by "wet" sanding.

I have run into some clear gloss coats at the hardware store that are water based and form increadably smooth glossy surfaces right on their own (compared to solvent based sprays). You need to be careful with these because sometimes they stick really well and sometimes they peel off like dry skin on an old person. :-)

The air-brush produces much smaller droplets than a spray can. I use a Badger and attached my cheap air compressor to a stand alone Sears air tank with its own regulator. The tank smooths out the air and gets rid of pressure drops and it was way cheaper than the obscenely expensive compressors with built-in tanks.

Spray cans are really good at filling in recessed panel lines if you're not really careful.

Jim Klein

One question that occurs to me... Are there benefits in warming (or actually heating) paint for use in an airbrush? Would the paint flow better or would there be adverse reactions with the relatively cool propellant, in my case, from my CO2 cylinder? Or, would it be a wash, benefits canceled by negatives?

Frank Kranick (who still marvels at the finish of many competitive auto models)

Well the warm paint might be thinner but the drop in temperature of the CO2 as it goes from high pressure to low pressure is pretty large and experimentation would be in order to see if warming the paint helps. When using a compressor and tank, room temp air increases in temperature as the pressure builds in the tank and then drops as the air is used. That is why we need the moisture traps. High pressure air holds more water and when the pressure drops in spraying, moisture comes out and needs to be trapped so it does not become part of the paint job. :-) Then again, the CO2 in the cans is dry and has no H2O.

I'd be really careful about heating the CO2 cans. Having a CO2 car racing around my hobby room at several feet/sec after it ruptures would really take all the fun out of modeling for at least a few hours. :-)

I'm sure it depends on the amount of paint heated and I'd be careful not to heat water based paints beyond the point where they might turn into "pudding". Good luck and I think we might all like to here how the heating helps (or not).

Jim Klein

It would be quite difficult in any case to heat the paint in a paint cup, perhaps easier in a jar. The main reason for warming a rattle-can is that the expansion of the propellant cools the can and thus the paint as well. In an airbrush, even using propellant cans, the paint is not cooled (since the cold can is at the other end of the air-supply hose).

Even the most basic of airbrushes atomises better than a rattle-can; the spray head is precision engineered in metal, compared to the moulded, throwaway atomiser on a rattle-can. This is the reason they give better results, more consistent droplet size and with an even spray-pattern.

Going upthread, there are several reasons for applying mutliple light coats, beginning with a mist coat.

A light, non-opaque first coat is easier to apply evenly and will not run, sag or ripple. An attempt to cover in one coat will usually result in runs in some places, as it isn't easy to tell how thick the coat is once it is opaque. Applying several mist coats on top of each other will give an opaque covering, but by allowing intermediate coats to dry, there is much less risk of runs. For a glossy finish, the final coat at least should be "wet", i.e. run together to form a continuous gloss.

One other advantage of several coats over just one is that the colour gains "depth". I think this is from internal reflections between the layers. This is also true for varnish coats, and is improved by rubbing down between coats; this to get the paint progressively smoother.

How hot should the water be?

Also, I forgot to bring up this question along with the previous ones. What about the primer paint? How many coats should there be? The plastic on my model is black and I know this would be primed since red is lighter than black.

Less than boiling 210 deg F

Also, I forgot to bring up this question along with the previous ones. What about the primer paint? How many coats should there be? The plastic on my model is black and I know this would be primed since red is lighter than black.