Painting 3D parts...

[Biggu]

Silly question time.... I apologize if this question has been asked and answered... I have a few 3D printed parts for my  large truck builds, and believe it to be plastic as the parts are quite flexible and 'feel' like plastic.... I don't believe they are resin...... and I am so far resisting the acrylic paints ( I know , but...) as I have had a lot of difficulty spraying them, and I prefer enamels.... question is, can I paint the 3D parts with enamel paints, ( Testors Model Master ) and if so is there any special prep work needed for the paint to stick and stay on said parts..... again, sorry if this has been asked and answered, I would appreciate any advice or experiences you guys have had with this....

Jeff

[ctruss53]

I totally avoid enamels. They take way too long to dry.

When painting 3D printed parts, plastic or resin, sand them smooth, or remove any construction leftovers like nubs or seams. Wash with warm soapy water. I use Dawn dish soap.

Then use a high quality primer. I prefer Tamiya or Mr Hobby spray cans. They are lacquer based dry fast, and bond to nearly anything.

Check for pits or texture you don't want, fill and re-prime as needed.

Then use acrylic or lacquer paints to finish.

Edited March 9, 2023 by ctruss53
"pits" not "puts"

[Exotics_Builder]

44 minutes ago, ctruss53 said:

I totally avoid enamels. They take way too long to dry.

When painting 3D printed parts, plastic or resin, sand them smooth, or remove any construction leftovers like nubs or seams. Wash with warm soapy water. I use Dawn dish soap.

Then use a high quality primer. I prefer Tamiya or Mr Hobby spray cans. They are lacquer based dry fast, and bond to nearly anything.

Check for puts or texture you don't want, fill and re-prime as needed.

Then use acrylic or lacquer paints to finish.

As stated, but I will also use enamels selectively.  I do have a dehydrator to help on dry time. 

[yh70]

YES YOU CAN paint them in Enamel Paint..i use Rust-oleum or Krylon rattle can spray paints & primer and they dont take long to dry at all. make sure u sand and clean the parts..i myself will soak them in 99% Isopropyl Alcohol for 2 minuets then wash in warm soapy water, rinse well..and if you like Testors Model Master paints then use them they nothing wrong with Testors paints..i have some my self...

[Biggu]

1 hour ago, yh70 said:

YES YOU CAN paint them in Enamel Paint..i use Rust-oleum or Krylon rattle can spray paints & primer and they dont take long to dry at all. make sure u sand and clean the parts..i myself will soak them in 99% Isopropyl Alcohol for 2 minuets then wash in warm soapy water, rinse well..and if you like Testors Model Master paints then use them they nothing wrong with Testors paints..i have some my self...

AWESOME !  Thanks for that... drying time for me isn't usually a big deal, unless it takes weeks or something crazy like that..... I have heard some oils take a while to dry , but that is another thing.... so by reading the other answers, it seems basically any paint should work.... I knew I came to the right place... thanks

[ctruss53]

Enamels take weeks to fully cure.

Lacquers only take a day or two.

[StevenGuthmiller]

If you’re airbrushing enamel, you can speed up drying time exponentially by thinning with lacquer thinner.

As an example, I sprayed this oil filter and starter with enamel thinned with lacquer thinner Tuesday night.

I added the decal to the oil filter, and painted the starter solenoid, (with Testors enamel) yesterday, and then sprayed a coat of Testors clear lacquer over both this morning.

Both are easily dry enough to handle this afternoon.

 

 

 

Steve

[Bills72sj]

I am an enamel fan too. While 3D printing does not have release agents like resin, washing the parts is a good idea. Go with a super fine lacquer primer just to make sure the surface is as you want it to be. Enamels thinned with lacquer thinner, airbrush really nice and only take a couple of days to be touchable. However, my parts tend to get 2 weeks of rest due to my batch building technique and my limited build time.

Both of my 4 post lifts are 3D printed and sprayed with enamel. No issues,

[Biggu]

Bill, your shop dio is awesome !!!  You are the second or third guy to mention thinning enamels with lacquer thinner............ I had NO idea that was a thing or even possible..... so if I have this correct, after reading all of the ideas presented here, is that if I were to thin enamel paint with enamel thinner, the paint takes a lot longer to dry on 3D printed items ? I find that as usual for me, enamels are good to handle after about 24 hours or so... I do know it does take a while for them to fully cure as mentioned here earlier, but as it is sprayed on 3D does it take longer because of what the 3D material is.....  sorry to be so thick guys... but this is relatively new territory for me....

[Bainford]

1 hour ago, Biggu said:

Bill, your shop dio is awesome !!!  You are the second or third guy to mention thinning enamels with lacquer thinner............ I had NO idea that was a thing or even possible..... so if I have this correct, after reading all of the ideas presented here, is that if I were to thin enamel paint with enamel thinner, the paint takes a lot longer to dry on 3D printed items ? I find that as usual for me, enamels are good to handle after about 24 hours or so... I do know it does take a while for them to fully cure as mentioned here earlier, but as it is sprayed on 3D does it take longer because of what the 3D material is.....  sorry to be so thick guys... but this is relatively new territory for me....

Nothing thick about that, ask questions until it's fully understood. Enamel paint (or any other) does not take longer to cure on 3D printed parts than it does on kit plastic. By nature, it's just slow to cure. Thinning with lacquer thinner helps speed up the cure time, regardless of what part you are painting. I think you'll find that most builders using enamel paint will thin with lacquer thinner. It has sort of become the 'go to' thinner for some time now. I am a regular enamel user, and I thin with regular hardware-store lacquer thinner, or Mr Color self levelling thinner (which is recommended for painting bodies, and is suitable for lacquer paint).

It's worth keeping in mind, too, that drying and curing are two different things, though the two terms are frequently used interchangeably. Paint can feel dry, but not be fully cured. Enamel can feel dry in a day or two, but may still take a week or two to fully cure. One trick is to use the sniff test. Smell the painted part close up. If you can still smell the solvents, it's not fully cured. Parts may be handled once they are dried for a while, but I recommend waiting until fully cured before polishing.

A food dehydrator can be used to speed up dry/cure times. However, I haven't used 3D printed parts in a dehydrator, so I can't personally recommend it, but it works great on kit parts. Perhaps someone can chime in with info on using a dehydrator with 3D printed parts. If you are interested in the dehydrator technique for your enamel (or any other) painting, there is a lot of information available on the forum. Here's a link 

 

Edited March 10, 2023 by Bainford
add link

[Biggu]

1 hour ago, Bainford said:

Nothing thick about that, ask questions until it's fully understood. Enamel paint (or any other) does not take longer to cure on 3D printed parts than it does on kit plastic. By nature, it's just slow to cure. Thinning with lacquer thinner helps speed up the cure time, regardless of what part you are painting. I think you'll find that most builders using enamel paint will thin with lacquer thinner. It has sort of become the 'go to' thinner for some time now. I am a regular enamel user, and I thin with regular hardware-store lacquer thinner, or Mr Color self levelling thinner (which is recommended for painting bodies, and is suitable for lacquer paint).

It's worth keeping in mind, too, that drying and curing are two different things, though the two terms are frequently used interchangeably. Paint can feel dry, but not be fully cured. Enamel can feel dry in a day or two, but may still take a week or two to fully cure. One trick is to use the sniff test. Smell the painted part close up. If you can still smell the solvents, it's not fully cured. Parts may be handled once they are dried for a while, but I recommend waiting until fully cured before polishing.

A food dehydrator can be used to speed up dry/cure times. However, I haven't used 3D printed parts in a dehydrator, so I can't personally recommend it, but it works great on kit parts. Perhaps someone can chime in with info on using a dehydrator with 3D printed parts. If you are interested in the dehydrator technique for your enamel (or any other) painting, there is a lot of information available on the forum. Here's a link 

 

Thanks for the great insight Trevor, I have and do use the 'sniff' test... and it seems to work well for my applications.... I just wasn't sure that with 3D if the plastic or resin used may have different properties to either slow drying the paint or not letting the paint adhere, or peal etc, etc... once again , I am behind the curve about the thinning of the enamel paints, looks like I may have to amend my ways... old dog , new trick thing..

[Bills72sj]

9 hours ago, Biggu said:

Bill, your shop dio is awesome !!!  You are the second or third guy to mention thinning enamels with lacquer thinner............ I had NO idea that was a thing or even possible..... so if I have this correct, after reading all of the ideas presented here, is that if I were to thin enamel paint with enamel thinner, the paint takes a lot longer to dry on 3D printed items ? I find that as usual for me, enamels are good to handle after about 24 hours or so... I do know it does take a while for them to fully cure as mentioned here earlier, but as it is sprayed on 3D does it take longer because of what the 3D material is.....  sorry to be so thick guys... but this is relatively new territory for me....

Jeff, Thank you. My diorama project was a fun build that went WAY over budget but it is pretty much exactly what I wanted.

Little Testors enamel bottles mixed 50/50 with Home Depot or Lowes lacquer thinner works pretty well. I use a Mr Hobby PS290 with a 0.5 mm nozzle. Some folks thin it 10% more for smaller needles. You can use the same lacquer thinner to clean your airbrush after you are done. If you have enamel rattle cans, you can decant them (safely) and spray it just as it is, or maybe thin what you get out, a little bit. The trick I have learned is to spray the first coat kind of a dry mist with a little too much distance until you have shaded the piece about 25-30% coverage. Pause and let it "bite" for a minute or two. Afterwards move in closer and adjust your speed and strokes until you have 100% coverage but is wet enough to self level. Don't be in a hurry but keep spraying/stroking until you just "get" a nice glossy piece. It is ok to pause the paint flow and just blow air if you feel that you are risking a run or sag. Then quit and let it cure. Try to avoid missing any thing so you do not have to add anymore coats. Watch out for transparent colors running away from any ridges. They may require more blow time. This is where a double action airbrush can show its benefit.

The paint really does not care what the plastic material is. Especially if you prime it first.

[Biggu]

LOL, that is like most projects, we seem to get on with, they usually go over budget... but in a good way... the results , in your case were well worth it in my eyes, it is really good.  When all written out the painting procedure sounds daunting, but in practice not so much, looks like I will have to stock up on some thinners... seems a bit technical.... but with the sound advice I am getting here I think I should be able to get some results.... I appreciate every word....

[Biggu]

I am also assuming...( I know.. but ).... that a rattle can of Acrylic Lacquer automotive paint could be used as well, with a primer of course? Even for regular styrene? I have always used specific enamel model paints....

Edited March 11, 2023 by Biggu

[stitchdup]

32 minutes ago, Biggu said:

I am also assuming...( I know.. but ).... that a rattle can of Acrylic Lacquer automotive paint could be used as well, with a primer of course? Even for regular styrene? I have always used specific enamel model paints....

I use automotive acrylic filler primer on my 3d prints and it seems to work for me. Its holts filler primer i use and i like it as it fills many of the print lines that are still there after cleaning up parts. Its also able to be used under enamels if you let it gas out for a few days but test first as i dont do this often and different paints vary.

[MrObsessive]

1 hour ago, Biggu said:

I am also assuming...( I know.. but ).... that a rattle can of Acrylic Lacquer automotive paint could be used as well, with a primer of course? Even for regular styrene? I have always used specific enamel model paints....

Be careful with "hot" paints on 3D printed resin. Depending on the part, I know for a fact that it can warp just as if it were plastic. I know this from getting several DM's where someone painted something with hot automotive paint/primer, and the part warped. I told them that to play it safe if they want to use that type of primer, it wouldn't hurt at all to use a barrier coat over the resin.

Some will say resin cannot warp from paint, but I can tell you this is not true. A few years ago I got a hood from The Modelhaus that I wanted painted. I painted one side of it with primer and color coat (automotive), and sure enough, the next day the hood had curled up.

The paint was "hot" enough that it pulled the part within itself to warp, and I had to strip the part and start over. I used a barrier coat called "BIN Zinsser" the next time, and I had no more issue. I recommend doing this even if you're unsure about the properties of the paint you're using, as not all 3D prints are created equal.

[Biggu]

 

21 hours ago, MrObsessive said:

Be careful with "hot" paints on 3D printed resin. Depending on the part, I know for a fact that it can warp just as if it were plastic. I know this from getting several DM's where someone painted something with hot automotive paint/primer, and the part warped. I told them that to play it safe if they want to use that type of primer, it wouldn't hurt at all to use a barrier coat over the resin.

Some will say resin cannot warp from paint, but I can tell you this is not true. A few years ago I got a hood from The Modelhaus that I wanted painted. I painted one side of it with primer and color coat (automotive), and sure enough, the next day the hood had curled up.

The paint was "hot" enough that it pulled the part within itself to warp, and I had to strip the part and start over. I used a barrier coat called "BIN Zinsser" the next time, and I had no more issue. I recommend doing this even if you're unsure about the properties of the paint you're using, as not all 3D prints are created equal.

Thanks, Bill.... so I went out yesterday and taking all advice under advisement, I bought some lacquer thinner, and primer .............so I will try to thin my Testors Model Master enamel paints with the lacquer thinner and give that a go.... maybe at first just on a regular kit, I have a GMC General truck kit I'm working on and I might give it a try on that one, ........... seems like I'm stepping out of my comfort zone a bit here, but what the heck... like my dad used to say, Nothing ventured , nothing gained.... I do appreciate all the ideas and advice I have received on this question...