Surface Prep Problems

[GMTrainNut]

Hi all, glad to have found this forum!

I used to do a lot of custom painting, then took a break from it for many years. Started up again about a year ago, and used the opportunity to make the transition from solvent based paints to water based. I'm primarily using Pollyscale now, and have gotten comfortable with it.

I am having some issues with surface preparation that I'd like to bounce off you guys. The first time I did some test painting with Pollyscale I followed my old procedure: Wash the shell in warm soapy water, rinse well, let air dry, and paint. Not sure if it's the water based paints or the fact that I moved and we have harder water here, but stains and splotches showed through the paint after it dried. Fortunately it was only a test shell so it wasn't a big deal.

Having read that distilled water might work better in cases like this I tried another shell, this time using distilled water and soap for washing. Only problem was rinsing, having to buy it in gallon jugs I couldn't exactly do a super thorough rinse. I tried to compensate for that by a short soak in denatured (or maybe it was 91 percent isopropyl), but I still wound up with some stains.

Now I got to the point where I was asked to paint something for a friend, and I resorted to a lengthy soak and scrubbing in alcohol, and it seems to have worked okay.

I'm guessing that I need some kind of water softener system, but in the meantime I'm still in need of consistent results sans tap water.

So I'm wondering if any of you have had similar issues, what methods you use to prep shells for painting. I try and avoid expensive alternatives like Floquil's Plastic Prep, but if that's the route I have to go I will do so.

Thanks for any tips!

 

[UP2CSX]

I use 91% alcohol for both prep and thinning. I avoid water as much as possible for the just the reasons you mentioned. You can had a covered tub of alcohol to soak models and them use a spray bottle of alcohol to rinse off any residue. I've also found it much more impotant to use a good acrylic primer when painting as this gives some tooth for the paint to grab onto. Solvent paints can be, to a certain extent, self-priming, but acylics will find every flaw if they are not primed first.

 

[GMTrainNut]

Many thanks for the reply! A few questions if I may...

How long do you soak the body shells for? Do you merely soak them or do you do any scrubbing with a brush?

What do you use for a primer?

Yes, I didn't have this problem with solvent based paints, but I'm not sure if that was because of the properties of the paint, or if the place I was living at the time had softer water.

Thanks again.

 

[Graham Line]

I give plastic a good rinse in Polly S plastic prep, which is reusable. A paper coffee filter seems to absorb some of the greasy stuff.
It's Polly S. #556007, costs about $8 a pint and lasts quite a while.
Ingredients are ethanol, propolyene glycol and methyl ether, so you want to keep it tightly capped. I generally use disposable aluminum pans to do the soak.

 

[UP2CSX]

I usually soak a shell for about 15 minutes to a half-hour, depending on how much crud I see coming off. I do a little scrubbing with a soft brush but find I don't need to doo much after the soak job. I then just spray rinse it with more alcohol and set it aside to air dry. The Polly S plastic prep is basically not much more than alcohol but it does work it you want to go that route. A word of warning though. Most plastic is safe with alcohol but there are some models that are made with a type of polystyrene that gets brittle when exposed to alcohol. If the model come with plastic spacers or horn hook couplers, I always throw those in the alcohol first and then leave it overnight. If the plastic is still in good shape, the model should be safe for alcohol.

 

[GMTrainNut]

Many thanks to both of you for your advice. I will definitely be abandoning the use of water for prep work. I'll experiment with alcohol and the Plastic Prep.

I too am careful about testing the plastic...I once managed to turn a Kato shell to goo by trying to strip it. I don't recall what I was using at the time, it was either Pine Sol or brake fluid.

Again, thank you!

 

[TMLW]

Break fluid is great for making goo! The Polly scale prep works great. I really like it. For primer i usually use pollyscale white or gray depending on what i am painting.

 

[Graham Line]

Very interesting watching the oily mold release agent float off an undec model when you give it a dip in your favorite prep solution. You'll never skip the step again.
I occasionally give complex areas a little scrub with a soft toothbrush, but that's about it. The advice about air-drying is important, and you want to handle the piece without leaving fingerprints. Bend up some tools out of brass wire to get pieces out of the soup.
Careful prep makes the paint lay down much more smoothly.

 

[UP2CSX]

I've used automatic transmisson fluid to strip stubborn paint and it works fine...as long as it's Dextron III. That stuff you get at the dollar store will turn a shell to jello in nothing flat. Brake fluid works sometimes but it's always risky. Pine-Sol usually works without damaging plastic but some forms of polystyrene will get brittle. I wouldn't use any of these for just washing a shell. Isopropyl alcohol will work much better and the chances of damaging the shell is nil.

 

[GMTrainNut]

91 percent isopropyl alcohol it is then! Just soaked and scrubbed a shell in it, after it's fully dry will prime light gray and see how it comes out.

Yes, stripping can be dicey! Kato and older Atlas/Kato seem to have been the easiest to destroy.

Thanks all.

 

[UP2CSX]

Yep, Kato and early Atlas shells, which I think were made by Kato, seem to have a secret paint process where the paint is welded into the shell. I've soaked and scrubbed for hours without removing all the Kato paint. With all that chemical exposure and physical damage from scrubbing, you're almost always going to damage the shell. I've gotten to the point I either buy Kato engines undecorated or with the paint scheme I want. I've long ago gave up the idea of stripping and repainting Kato shells without loosing an unacceptably high number to damage.

 

[GMTrainNut]

Just had another thought...I use a water/ammonia mixture to clean the airbrush after use. And I usually rinse all the parts under running tap water. Which means minerals and "stuff" might be building up inside the airbrush as it dries. I sure can't see buying gallon jugs of distilled water for cleaning and rinsing. Do you guys think it would be okay to follow this procedure, but then follow it up with a soak and rinse of all parts in denatured or 91% alcohol? Would that take care of the hard water problem, or do I really need to figure out a workflow that completely eliminates tap water?

Thanks as usual, don't mean to beat a dead horse just really want to get this figured out, I have a lot of locos to paint!

 

[UP2CSX]

How hard is the water at your place? Does it build up scale in shower heads and faucets? If not, I don't think cleaning the airbrush is going to leave enough mineral residue behind to matter, as long as you let it air dry between sessions. If your water is really hard, you may be able to get purified water at the grocery store. It's a lot cheaper than distilled but has most of the minerals removed. I'd be concerned that using straight alcohol for cleaning on a regular basis would eventually give you problems with the seals.

 

[stationmaster]

I found an old vibrator-type jewelry cleaner at a flea market. At least that is what I think it was use for. In my usual fit of madness I bought it for use in cleaning shells. I'll be damned if it didn't do the job. I was vindicated!!! And my better half still thought I was nuts!!! I pour the used solution through a coffee filter, as mentioned before. Anything to save a nickel and get the job done.

To dry the shell off, I use the compressor that I use for the air brush that has a little nozzle. Pffft, pfffftt, pffftt. And it's dry.

Bob

 

[GMTrainNut]

Jim,

I don't think the water is really hard here, it only builds up a very little at a time around faucets etc. So maybe I don't have to take it to that extreme.

Good point about the seals, the Badger I use has one internally that I gather isn't easily replaced.

Bob,

Is that like one of those ultrasonic cleaners that they used to advertise in model rr magazines? I knew a guy that had one and he said it was great for cleaning out gummed up mechanisms too.

 

[Graham Line]

Yep, Kato and early Atlas shells, which I think were made by Kato, seem to have a secret paint process where the paint is welded into the shell.... I've long ago gave up the idea of stripping and repainting Kato shells without loosing an unacceptably high number to damage.

I give Kato engines a soak in Easy Lift Off or Chameleon or something like that (usually takes the lettering and striping right off) then give them a gentle scrub with a soft toothbrush and Bon Ami to take the gloss off the remaining paint. Rinse it off. Then I just spray the paint. If the solutions don't take it off, it's just a good undercoat.

On the airbrush, I clean with a jug of discount windshield washer fluid from the auto parts store, wipe everything down before reassembling it, and then run some air through it before putting everything away.

 

[Espeefan]

Yep, Kato and early Atlas shells, which I think were made by Kato, seem to have a secret paint process where the paint is welded into the shell. I've soaked and scrubbed for hours without removing all the Kato paint. With all that chemical exposure and physical damage from scrubbing, you're almost always going to damage the shell. I've gotten to the point I either buy Kato engines undecorated or with the paint scheme I want. I've long ago gave up the idea of stripping and repainting Kato shells without loosing an unacceptably high number to damage.

I have heard that Pine-Sol will lift this paint without damaging the shells. Not sure about generic brands but the real stuff is supposed to work. The soak time is long, so be patient.

 

[UP2CSX]

Alan, I've used Pine-Sol and it works about 20% of the time. The rest of the time, the shell just sits in the tub staring back at me laughing. I don't know what the deal is with some Kato paint but it's about the toughest thing in the universe.