Testors Spray Paint Won't Dry

[BCR751]

I applied some Testors rattle can primer to a item that I'm building three days ago and the stuff is still tacky.  I hit it with low heat using a heat gun but it had no effect.  Anyone else had this issue with Testors spray primer?

Doug

[thomasjmdavis]

Well, always possible it is bad paint, but question 1 for me would be- what is the material that you sprayed?

The only time I can think of in the last 30 years, that I have had the problem, was with a 3D print before I learned that I needed to UV cure it (sunlight) even though it was supposedly "ready for paint".  Now I leave all my 3D purchases on the kitchen window sill for a few days. I have had the issue with "full scale" paint.   But a few questions that would help diagnose the issue-

1) Was the paint old enough that the "driers" had dissipated?  Or, had just been sitting for a long time, and needed more shaking to be properly mixed.  Even if you bought it yesterday, that is no guarantee that it wasn't sitting in a warehouse for 5 years.  Last brick and mortar hobby shop I visited still had a couple colors of Floquil on the shelves,  and had one Accupaint still on the shelves a few years ago.  Just sayin' - hobby shops never throw this stuff out.

2) What is the material being sprayed?  Is it compatible with the paint?  If 3D printed, was it fully cured?

3) Was the surface clean of oil?  I've caught myself a couple times, after cleaning a model, handling it a lot more than I should.  Although that is usually just a thumbprint  showing up in the finish, not tacky paint all over.

4) Was there already some form of paint on it?

[BCR751]

Well, always possible it is bad paint, but question 1 for me would be- what is the material that you sprayed?

The only time I can think of in the last 30 years, that I have had the problem, was with a 3D print before I learned that I needed to UV cure it (sunlight) even though it was supposedly "ready for paint".  Now I leave all my 3D purchases on the kitchen window sill for a few days. I have had the issue with "full scale" paint.   But a few questions that would help diagnose the issue-

1) Was the paint old enough that the "driers" had dissipated?  Or, had just been sitting for a long time, and needed more shaking to be properly mixed.  Even if you bought it yesterday, that is no guarantee that it wasn't sitting in a warehouse for 5 years.  Last brick and mortar hobby shop I visited still had a couple colors of Floquil on the shelves,  and had one Accupaint still on the shelves a few years ago.  Just sayin' - hobby shops never throw this stuff out.

2) What is the material being sprayed?  Is it compatible with the paint?  If 3D printed, was it fully cured?

3) Was the surface clean of oil?  I've caught myself a couple times, after cleaning a model, handling it a lot more than I should.  Although that is usually just a thumbprint  showing up in the finish, not tacky paint all over.

4) Was there already some form of paint on it?

Thanks for the reply Tom.  This is my first time using a rattle can to paint anything.  I've always bit a bit leery and tried to stay away from using it.  Always went with an airbrush.  To answer your questions in order:

1.  The paint has been sitting on a shelf for probably 10 years.  I did shake the begeesus out of it prior to painting.

2.  This may be the problem.  The item was 3D printed.  I don't know what the medium was.  I'll have to ask John B.  He did the print.  All I did was wash the item in warm water and mild detergent.

3.  See #2's answer.

4.  No, it was bare resin.  As mentioned, I don't know what type of resin was used but it doesn't look like anything I've seen previously.

If the item wasn't properly cured, how do I get the paint off without wrecking it so I can start over?  The paint is enamel so it won't be easy.

Doug

[John]

Doug -- I cured the parts before I sent them out .. while it's possible you didn't get a complete cure I would bet the paint is the culprit. I use gray rattle can primer from wal mart ...

You should be able to strip the paint using alcohol ..  The resin is standard anycubic grey so thats a common resin that should hold a paint

[peteski]

I agree the there is some sort of interaction or incompatibility between the item being painted and the paint.  This is true with polyurethane resins or 3D printed resins.

[Angus Shops]

I’ve used Testors Model Master rattle can paints as a ‘primer’ on my resin castings for years, with generally great results. However, if the resin used in the casting isn’t ‘fresh’, that is, from a recently purchased batch, the resin may not cure properly. In this case the Testors does not cure and will remain sticky and will take fingerprints and etc.

I’m going to miss Testors. A non railroad oriented LHS still has a few cans in stock (at exorbitant prices); I’m going to have to go clean them out of suitable colours before I regret my championship level ability to procrastinate.

[muktown128]

My son bought a couple of plastic car model kits and wanted to but some paint.  I have some old jars of Testors paint from when I was a kid that I will try to resuscitate for my son.  Some of the jars have the prices on the caps ($0.39).  I'm guessing these are probably around 40-45 years old.  I was going to add some paint thinner and see what happens. 

[John]

I’ve used Testors Model Master rattle can paints as a ‘primer’ on my resin castings for years, with generally great results. However, if the resin used in the casting isn’t ‘fresh’, that is, from a recently purchased batch, the resin may not cure properly. In this case the Testors does not cure and will remain sticky and will take fingerprints and etc.

The resin was well within the "use by date" .. I also printed other parts with this batch that primed up ok ..


https://www.therailwire.net/forum/gallery/25/3-210921111728.jpeg

[BCR751]

I'm tending to go with bad paint as the culprit given that it's been on my shelf for at least ten years.  I also painted some styrene and the paint is sticky on that as well.  I will try using IPA to remove the existing paint.  Not sure what other remover to use if that doesn't work.

Doug

[robert3985]

If the paint isn't drying and it's enamel, maybe just plain old "paint thinner" would work to get it off.  Even though I've used enamel paints (Scalecoat II) on several of my prints without any ill effects, I haven't ever used just paint thinner on any of my Anycubic grey prints for any purpose, so I'm not sure what (if any) negative things paint thinner might do to that particular resin.  My initial gut feeling is that the print will be okay....but, it's just a feeling.

Cheerio!
Bob Gilmore

[peteski]

My son bought a couple of plastic car model kits and wanted to but some paint.  I have some old jars of Testors paint from when I was a kid that I will try to resuscitate for my son.  Some of the jars have the prices on the caps ($0.39).  I'm guessing these are probably around 40-45 years old.  I was going to add some paint thinner and see what happens.

I still have these paints (and they are still liquid). 



As far as reviving enamels goes, if enough solvent evaporated that they have turned into rubbery or gelatinous consistency then no amount of any type of thinner will turn them into usable paint.  Unlike dried lacquers (which can be dissolved again), when enamels dry (harden) their chemical composition changes and they will nto turn back into liquid.  Strong solvents will turn hardened enamel into gooey gel, but even if you were to try blending the gel back into liquid, all you will end up with is small chunks of hardened enamel suspended in thinner.  At least that is my experience.

But if the enamel is still in liquid state, adding thinner should make it usable again.

Funny thing is that I also just realized that the old Testors logo looks quite similar to Tesla (electric automobile) logo.  I wonder of the Tesla logo designer used to build plastic models as a kid. Hmmm . . .Probably not. I suspect that the person who designed the Tesla logo was nor even born a the time Testors used that Stylized "T" as a logo.

[MK]

How do you keep them liquid after all these years (decades?) ?  Make calendar reminders to add solvent a few times a year? 

[thomasjmdavis]

And I thought my projects dragged on for a long time....even so, all my 15cent bottles of paint were used up 45 years ago.  Maybe 50.  When did they raise the price to a quarter?

[ncbqguy]

I have bottles of Testor’s Pla that date back to 8th Grade (1958!). Even better, I have some Super Model Railroad lacquer bottles that are still good that may go as far back as 1949.  Johnny Super was a one-person Model Railroad distributor who bottled his own line of paint and carried supplies in a bread type truck to the many LHS that existed in the Chicago area back then.   My dad bought them to paint a S Scale  ALCO S-1 cast metal kit powered by Miller Laboratories axle motored power trucks. 
One of these days I have to start thinning out my collection...
Charlie Vlk

[peteski]

How do you keep them liquid after all these years (decades?) ?  Make calendar reminders to add solvent a few times a year? 

Well, the bottles are glass. If you clean the lip and the gasket in the cap really well, and screw the lif on tight, the solvent should not evaporate (or evaporate very, very slowly).

I have to fess up that the 15 cent bottles are not mine. Those were before my modeling time. I got them from an older friend of mine when he was purging things for a move to another house.  I have not opened them, but the contents is still (slightly thickened) liquid.  The 25 and 30 cent bottles were purchased by me in the late '70s and '80s. I might have added some thinner to them long time ago, and they are still usable now.