Rattle can blues

[Speedfreak]

Today I decided to paint some of the suspension/chassis parts for a '71 Duster I started years ago. The weather was close to perfect, 61 degrees, 21% humidity (that's unheard of around here!), moderate winds 10-20mph. Ya, the wind was a little strong but I was painting in my garage. So, I get everything mounted for painting, warm the paint in water (3oz. Testors gloss black), get all my stuff ready and proceed to the garage for what I'm hoping will be a successful experience. (I even got a respirator today!) I leave the garage door open half-way for ventilation and put on my gloves and respirator and head to the middle of the garage so I am away from any potenial wind gusts and I'm under a sky light in the roof for good vision. I grab the first part and start to spray, it looks good! Nice and shiney black! No runs! Just a light coat, but, it covered well so I'm thinking that will be enough. Grab the second part, same results. On my way back for the third part I decide to look at the first part to see how it's doing, (have the paint grimlins desended on my modeling world again?) and there they are! BUBBLES! AWWWWWWWWWWWWWW! My heart sinks, WAIT! Maybe they're bolt heads I didn't notice! YES! It's black paint, hard to see details/shadows etc,.. Look closely,..............bubbles. I'm quiting! That's it! I can't paint! Too much money invested, must continue Grab third part and pray for miracle, paint gods don't hate me, do they? Change distance of nozzle from part, get closer, more paint, that's it! No! Wait! Not that! Sure disaster! Go slow, smooth flow, pray for proper distance. Third part looks good, pray some more. Second part now has bubbles appearing, never mind that! Keep going, (LOL) bubbles sometimes shrink! YES! They'll all disappear gassing out! How is this happening? Will I ever know? Some of the parts don't look too bad, only minute bubbles. Go back inside, think about why I persist. Read more about painting on MCM. Get some help Maybe there will be some answers. The respirator worked very well. Cheers.

[LoneWolf15]

Did you shake the can ? That wasn't in your step by step description ...... ?

[FordRodnKustom]

Surface contamination on the parts?

[Tom Geiger]

^{Your problem comes down to one word "Testors". I use Duplicolor automotive paint nearly exclusively. Yes, I have to prime my parts to protect the plastic, but that gives me a chance to check for any imperfections before I spray color. I seldom have an issue.}

[slusher]

l use krylon semi gloss black and no primer on chassis. All paint you have to shake well. lf you had a respirator on l would have opened the door after paint. Might have put too much paint down at one time. Lite coats are better then 1 heavy one...

[cobraman]

Did you wash the parts ? Did you prime ? Did you over heat the paint ? As said already......light coats. You can get good results using Testors.

[Ace-Garageguy]

I've had similar bubble problems with Testors rattle-can enamels, yes sir. Occasionally, but it's happened...for no apparent reason. Are you shooting enamel ?

[High octane]

I really don't seem to have a problem spraying Testors, Tamiya, or Duplicolor in rattle cans. Maybe I'm just lucky?

[Ace-Garageguy]

I really don't seem to have a problem spraying Testors, Tamiya, or Duplicolor in rattle cans. Maybe I'm just lucky?

I never have a problem with Testors straight lacquers or basecoat / clears, or most of their enamels...BUT, the dark red enamel i shot on the wheels of my black '32 wedge-channeled car bubbled and popped to beat the band.

[1930fordpickup]

Could the age of the paint have an effect?

[Speedfreak]

LOL!

Could the age of the paint have an effect?

Maybe the age of the painter?

Donn, I did shake the can for over two minutes prior to going out into the garage, but , once in the garage and painting I was not shaking it as much as I normally would between parts.

Ron, the parts I painted today were prepped years ago and in a baggy (closed) that was kept in the model box inside another larger box. And I'm sure I washed them after sanding/prepping.

Tom, Yes, it could be the Testors, seems like pretty crude paint, but it's probably something I'm doing, or , not doing.

Carl, As I stated above I shook the paint well prior to painting, but , during the actual painting process itself not so much. The garage door was open a little more than half way. I don't think I was putting on too much paint, funny thing is, the one part that i did put a fairly heavy coat on (after panic set in) does not really have any bubbles. I do seem to have a problem with 'light' coats though. Because it always looks like to me that imperfections are beginning and I panick and proceed to apply a heavier coat.

Ray, Washed, yes; Prime, no; Paint heated with tap water; I do have a problem with 'light' coats, as stated above I always think something is going wrong when I apply light coats, or, attempt to apply light coats.

Bill, Yes, plain 'ol Testors enamel. Yikes!

Nick, Glad things are going well for you, send me some of that luck will you? AWWWWWWWWWWW!

Andy, The paint was brand new, just bought it today at local HL.

Ok, here's possible problems, jees,..........

1) Paint not shaken enough while/during painting process.

2) Nozzle too close/far away; I'm holding the can 6-8" away from object, sometimes maybe 8-10".

3) Too much paint; That has been a problem for me in the past, things start to look bad and I panick and start shooting heavy to cover up, which only turns into more/worse problems, today though only one part painted heavy and 'that' part,...ya, it looks like it has too much paint.

4) Take Ativan prior to painting, or , something more organic, Wait! What's this doing in here!

4) No primer; I did not prime the parts I painted today. But, I've never really used primer, ever. 'Sometimes' I do nowdays, at least on the bodies I do I'm always afraid I'll loose detail!

5) Paint itself; Testors.

Ok, there it is. The chorus and first verse of 'Rattle Can Blues.

My sincere thanks to those who have responded so far. Someday I'll be better at this.

Gene (the bean) Ahart

Edited November 20, 2013 by Speedfreak

[High octane]

I very seldom use enamels in the rattle cans, and maybe that's a good thing?

[Erik Smith]

Your better off with bare plastic than putting the dreaded Testor's enamel sprays on. They get old and bubble - and it seems they are ALL old.

[slusher]

Gene, for black try Krylon simi gloss in the short cans at hobby lobby. l have used testor paint for years and no bubbles ever. l have never warmed my paint and that makes it thinner. All you need is room temp paint...

[Jantrix]

^{Your problem comes down to one word "Testors". I use Duplicolor automotive paint nearly exclusively.}

x2

[Tom Geiger]

Primer is a must! It makes a huge difference! I primer every single part on every model I build even if I plan on brush painting a few parts. It makes the paint cover so much better which allows you to use less paint. It will also prevent paint from wicking away from sharp edges and pooling around panel lines. I use Plasti Kote sandable primer exclusively. It goes on thin, dries smooth and doesn't obscure details.

I agree completely! I can't get Plastikote here, so I use Duplicolor gray automotive primer, which is very similar. These primers go on very thin and don't obscure detail at all. Typically, automotive lacquers dry very flat and close to the surface even when put on in liberal coats.

[Ace-Garageguy]

I agree completely! I can't get Plastikote here, so I use Duplicolor gray automotive primer, which is very similar. These primers go on very thin and don't obscure detail at all. Typically, automotive lacquers dry very flat and close to the surface even when put on in liberal coats.

Yup.

Primer is a must! It makes a huge difference! I primer every single part on every model I build even if I plan on brush painting a few parts. It makes the paint cover so much better which allows you to use less paint. It will also prevent paint from wicking away from sharp edges and pooling around panel lines. I use Plasti Kote sandable primer exclusively. It goes on thin, dries smooth and doesn't obscure details.

Bubbles are usually caused by holding your paint can too close. The propellant will get trapped under the paint and as it escapes, will cause the dreaded bubble effect.

What made me start primering all of my parts was that I always had trouble spraying engines and chassis' (if I used a gloss paint on the chassis). The paint would always wick away from the high areas and pool in the low areas. One day, when I was primering a body, I decided to primer my engine and transmission to see if it would help my paint coverage. When I sprayed my engine with paint, I was amazed at how well the paint covered! One coat of paint and it was covered perfectly! I then proceeded to primer the rest of my parts and haven't looked back since. I won't even consider painting over bare plastic anymore!

Yup yup.

[Speedfreak]

Thanks you guys, looks like I'll be using primer on all my stuff hereafter. The bubbles aren't so bad that with a little sanding they'll be gone and I can apply a second coat of Model Master gloss black this time.

I just did a search and I can get Plastikote here; Which one of their primers do I want to get? They list several, one is for plastic, is that the one to get?

Thanks.

Edited November 20, 2013 by Speedfreak

[Art Anderson]

Today I decided to paint some of the suspension/chassis parts for a '71 Duster I started years ago. The weather was close to perfect, 61 degrees, 21% humidity (that's unheard of around here!), moderate winds 10-20mph. Ya, the wind was a little strong but I was painting in my garage. So, I get everything mounted for painting, warm the paint in water (3oz. Testors gloss black), get all my stuff ready and proceed to the garage for what I'm hoping will be a successful experience. (I even got a respirator today!) I leave the garage door open half-way for ventilation and put on my gloves and respirator and head to the middle of the garage so I am away from any potenial wind gusts and I'm under a sky light in the roof for good vision. I grab the first part and start to spray, it looks good! Nice and shiney black! No runs! Just a light coat, but, it covered well so I'm thinking that will be enough. Grab the second part, same results. On my way back for the third part I decide to look at the first part to see how it's doing, (have the paint grimlins desended on my modeling world again?) and there they are! BUBBLES! AWWWWWWWWWWWWWW! My heart sinks, WAIT! Maybe they're bolt heads I didn't notice! YES! It's black paint, hard to see details/shadows etc,.. Look closely,..............bubbles. I'm quiting! That's it! I can't paint! Too much money invested, must continue Grab third part and pray for miracle, paint gods don't hate me, do they? Change distance of nozzle from part, get closer, more paint, that's it! No! Wait! Not that! Sure disaster! Go slow, smooth flow, pray for proper distance. Third part looks good, pray some more. Second part now has bubbles appearing, never mind that! Keep going, (LOL) bubbles sometimes shrink! YES! They'll all disappear gassing out! How is this happening? Will I ever know? Some of the parts don't look too bad, only minute bubbles. Go back inside, think about why I persist. Read more about painting on MCM. Get some help Maybe there will be some answers. The respirator worked very well. Cheers.

I'm surprised, given that this has been discussed several times on this and other model car forums. This is a problem that I've experienced with spray-can enamels from more than 50 years ago (I first used hobby enamel sprays more than 50 years ago--started with Pactra's spray 'Namel paints). It's also the principal reason I went to airbrushing nearly half a century ago, and try to avoid enamel spray cans altogether. Lacquer sprays can do this, but in my experience--pretty rarely.

Unlike lacquers, which dry entirely from the evaporation of the solvent (thinners), enamel paints tend to dry by first "skinning over", and then dry much more slowly after that. Humidity appears to accelerate that "skinning over" of enamel paints, which can trap the propellant (compressed gas that pushes the paint out of the can through the spray nozzle) before it's had time to evaporate completely out of the paint. Those minute gas bubbles can tend to collect together (ever notice how the bubbles in a glass of beer or soda start out small, then grow larger as they "collect together"?), but if they are prevented from popping or otherwise evaporating out of the still liquid paint by even a very thin membrane of somewhat drying paint across the surface--they simply get larger to the point they become very visible to the naked eye.

It's not a fault of the spray can or its nozzle, nor is it a surface contamination issue (which causes fisheye, where the paint actually "runs away" from a speck of silicone or greasy contaminant) but a matter of both temperature and humidity. Lower temperature can exacerbate the problem by slowing the process of "outgassing" enough to prevent the propellant gasses from dissipating before the enamel paint starts to "skin over" as the drying process starts. Hot humid summer air can cause the very same problem as well, by accelerating the skinning over of the paint surface before the gas has sufficient chance to evaporate out of the paint (bear in mind, the propellant gas in spray paint is, in part, dissolved into the paint in the can--much like carbon dioxide in a can of soda or beer).

Solution? Try for at least room/shirtsleeve temperatures, either indoors or outside, and low humidity.

Art

[Ace-Garageguy]

Nice post, Art. Great to have the science of what's actually going on so intelligently presented, with the cause-and-effect relationships clearly explained, to folks who don't already know it.

Edited November 20, 2013 by Ace-Garageguy

[Speedfreak]

Thanks Roger for the info on the Plastikote.

Art, thanks for taking the time to write such an in-depth response, it has not gone unheeded.

In general, thanks to all who have responded to/followed this thread.

[Tom Geiger]

Since it came up in this thread. I know that both Plastikote and Duplicolor are owned by the same company. Here on the east coast, we saw Plastikote go away and be replaced with Duplicolor in stores in Pep Boys. I don't see Plastikote for sale anywhere.

Did they regionalize these brands? I was told the Plastikote name was going away.

[Art Anderson]

Nice post, Art. Great to have the science of what's actually going on so intelligently presented, with the cause-and-effect relationships clearly explained, to folks who don't already know it.

No science on my part--just observation and thinking it through years ago. As a teenager, I got a very large room in our newly expanded basement, and living in Indiana, our relative humidity can be almost tropical at times. My learning of what I described came from decanting rattle can paint for use in my airbrush (which I had the good fortune of being able to afford just after Christmas 1961 (thanks to customers on my morning paper route and their generous tips!). I noticed that the Pactra 'Namel spray paints foamed up just like soda pop when I sprayed them into my color jar, and having already learned how enamel paints dried (from the outside in) in Jr Hi and HS shop classes--I was able to simply put two and two together.

As soon as the AMT Lacquers came out, whenever possible for color, I changed to those, and with those lacquers (in their behavior almost identical to today's Tamiya and Modelmaster lacquer sprays) the problem ended.

Just one of the earliest real learning experiences in model building for me.

Art

[Ace-Garageguy]

No science on my part--just observation and thinking it through years ago.

"just observation and thinking it through"

That's really a pretty good definition of science.

[ToyLvr]

I've followed this thread and Gene's other recent threads on painting woes.

Have had a lot of similar problems, even though I've tried to follow all of the "rules" of prep, atmospheric considerations, etc, etc.

I cannot seem to find even one (1) paint system that will produce *consistent* results. Have even encountered problems with the much-vaunted Tamiya paints.

Have had some good results with some of the Testors product, bad results on other occasions. Tamiya seems to be a bit better and consistent, but too expensive.

I've often wounded how long some of these cans have been sitting on he shelf, and whether that has any effect on paint quality and/or dispensing.

Gene, I feel your pain! It's like you need some sort of anti-Voodoo mojo to ward off evil paint problems. ;-)

Still, I keep on trying.....

Hang in there!