Discussion on painting using a "rattle can"

[salmon]

Recently, I have come across several articles about not shaking your can of paint because it creates bubbles......
Here is one article that says that:

https://formlabs.com/blog/priming-3d-printed-parts/?utm_medium=email&utm_source=direct&utm_campaign=email-nurture&mkt_tok=eyJpIjoiTjJNeVl6STBPVE5sTkRWaiIsInQiOiI3VVd1bnoyQ2NkSGFua09STSthUnRlTXFMNWFENlBZeENYWXJudG5qSFlpbTZ5ejA0N3NvY1A3YTFpVSt6b2pZN0FIUWp2UlBZQ1NCWkdMZlI2SFRsQjdmMzV4MWlSeTM1RnRScXhSYmI3Qlp1U2VXT1ZBcGVxZmNVN216NVJQUiJ9

In the past 50 years (I am older than 50), this is new to me......I try not to be a stubborn old guy, but I need your thoughts and wisdom. Is this something new? What do the bubbles do?

[JWLaRue]

Tom,

I've always vigorously shaken any rattle can paint I've used and don't recall ever seeing bubbles in the painted surface. I (also) warm the can prior to and after shaking in a bath of hot water...so that may have an effect. I do find that warming does improve the evenness of the coat of paint.

It's definitely worth a trial or two of the swirling method to see if there is any difference.

-Jeff

[scott t]

Shake it like a polaroid picture! Then let it set awhile for the bubble to rise to the top.
My un-scientific opinion.

[sam reichart]

I've never had bubbles after shaking the can and I used to use red oxide automotive primer for my lower hulls...

[salmon]

O.K. so far it is the same experience that I have had, no issues with bubbles. I will see if I can contact the author and get his perspective.

[bob_eissler]

I've always done it like Jeff said. The biggest problem is a clogged nozzle. Hold the can upside down until only solvent comes out. Also, always start and stop spraying off of the model.

[chips]

I just went to my shop and checked the spray cans that I have. Testor's, Tamiya, Rustoleum, and Minwax varnish all say to shake vigorously after the ball starts moving. When using rattle cans, I always shake them.

The only thing I disagree with is the use of a tack cloth. I've used them in the past, and had some paint adhesion problems; apparently due to some of the tack cloth adhesive remaining on my work piece. I never use a tack cloth. I wipe down the part with a rag damp with lacquer thinner or denatured alcohol.

[eckloss]

I'm not so sure, but there could very well be bubbles. But I'd think they would get obliterated when the paint is expelled through the nozzle. Never really had issues with rattle can paint. Except Rustoleum. Screw that sh!t

[subdude]

Except Rustoleum. Screw that sh!t

Yeah. This X2.

Rustoleum has to be the most miserable crap in a can. Drying time measured in fortnights.

And ever since they changed Krylon to be "primer and paint all in one can", it sucks also.

Jim

[salmon]

Still trying to get in contact with author, but I asked Tamiya support. Here is the response I got:

Dear Tamiya Customer,

One isn’t better than the other, it’s all personal preference; in fact, that’s the first I’ve heard of rolling the can to prevent bubble? Try both for yourself and see if you notice a difference? Now for jar paints, shaking will create bubbles, it’s best to carefully stir jar paints.

Thank you,

Gary Demory
Tamiya America
Customer Service Supervisor

[salmon]

I got a response from FormLabs, not the author (although I did ask for him)

Hi Tom,

Thank you! I've got sculpture experience myself, so I'll be happy to weigh in. Swirling versus shaking comes down to preference, mostly—shaking can definitely introduce bubbles when done aggressively, so swirling is a "safer" bet, albeit a process that takes a little longer. Swirling also has the benefit of listening for that pea as a good measure that the solution is totally mixed-in, while shaking will just cause the pea to rattle around.

Overall, you may want to try a little experimenting to see what works best for you! The most important tip I can offer is keeping your distance from the part as you spray—getting too close will easily result in uneven coats splashing, and bubbling. I hope this information helps! Let me know if you have any other questions with regard to painting your parts.

Kelly Hicks
Formlabs Services | Customer Care



So, from what I am seeing is this is just a new trendy way to do something, but no scientific or logical reason. I will stick with the James Bond "Shaken, not stirred" approach.
Peace,
Tom

[JWLaRue]

I agree....just don't forget the olive! LOL!

-Jeff