What type of Primer?


ken_23434

ken_23434

Member
Before painting a plastic engine or car, is the standard to use regular old primer in the spray can from an auto store?

I know I have seen Krylon specifically made for plastics, but it wasn't primer. They may have had primer specifially for plastics, I just haven't lnoticed it. I was worried that the solvent used in regular primer might react in some way with the plastic and that is why Krylon had the special stuff for plastic.
 
I buy the $.96 spray can of gray primer from Wal*Mart's hardware department. The Wal*mart brand. It's very thin, and does not fill in fine details. I've never used auto primer, I'd assume it would work, but it may be thicker, this is just the el-cheapo stuff.
 
Krylon have both a red oxide primer, and a medium gray primer, neither are fully flat, more of a semi satin finish...
a bit thicker than the cheapy walmart primer, may be an issue with multiple coats, but covers well, quick dry time..
got them at walmart.
 
I almost never use primer on plastic. It's not necessary unless you're putting white or yellow or a light color over black plastic, or you've done a lot of kitbashing, patching etc. and need a solid base for a lighter color.

Andy
 
I do use primer over bare black plastic and when I need a neutral base for the model color. I like the Krylon medium gray and beige primer. Both give a nice, even coat and aren't too thick. As Andy says, primer on most plastic isn't really needed as long as the existing model color doesn't present coverage problems. The most important thing is a good wash with water and dish soap and letting it air dry. This removes both mold release compounds and the little bits of crud that are always on every model and look like boulders when you spray paint on them. :)
 
el3637 said:
I almost never use primer on plastic. It's not necessary unless you're putting white or yellow or a light color over black plastic, or you've done a lot of kitbashing, patching etc. and need a solid base for a lighter color.

Andy
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:eek: Heh, to repeat knowledge handed in a thread... Use primer, 100% of the time, even if the paint you're using does not require it. It will provide for smooth coats and better adhesion.

Not to criticize though, I've done allot of painting myself w/o it, and I always get better quality finishes with it.
 
Thanks for the advice. I am planning on painting some undecorated stuff I have. So, I will be putting the first layers of paint on them. The primer being thinner at Wal-Mart sounds like good advice. That, and it's cheap. :D
 
jbaakko said:
:eek: Heh, to repeat knowledge handed in a thread... Use primer, 100% of the time, even if the paint you're using does not require it. It will provide for smooth coats and better adhesion.

Not to criticize though, I've done allot of painting myself w/o it, and I always get better quality finishes with it.
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Since much of what I paint is either dark colors (blue or black), or something close to primer gray anyway (I use MofW gray on my N&W covered hoppers), I rarely have any need for primer. I don't like to add thickness when I don't have to. For many years Proto 2000 undecorated locos all came in gray primer - I stripped it before painting my base coat. I found it actually reduced adhesion - the one loco I painted over the primer - Floquil dark blue - there are some places where the blue rubbed off. Never had that problem on bare plastic. Fortunately Proto finally gave up with the primer. It also gets in the way of any shell alterations. It does strip easily and nearly 100% cleanly with 91% isopropyl alcohol.

Andy
 
First off a word about Krylon Fusion (the stuff made for plastic).

Put the can down gently and run away quickly. That stuff might work great for outdoor furniture and stuff, but it has a little bit of texture, does not strip off at all, and jsut plan bites for models.


Always prime. Always always always. even if you are painting over a factory coat. prime it!!

I use either the standard krylon primer (red or grey dependign on the over coat) and regular Krylon sprays. (ahh the joys of free-lancing... I don't have to color match!!).

The difference I've noticed between priming and not, it make the job a whole lot easier but laying down a good base coat, and you dont have to go as thick with your final color.
 
el3637 said:
I almost never use primer on plastic. It's not necessary unless you're putting white or yellow or a light color over black plastic, or you've done a lot of kitbashing, patching etc. and need a solid base for a lighter color.

Andy
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AMEN! I will use Floquil Primer throgh the airbrush on brass, but never plastic UNLESS there is a very light color involved. Ive never had any adhesion problems,(50+ locos and I cant guess rolling stock and structures) but I think this even may be more due to cleanliness!
Yes, you Mother WAS right. Cleanliness is next to godlyness (sp?) All body shells get a thorough bath in warm soapy water. Dawn dish detergent is great for this. Then a complete rinse. At that point the shell goes on a painting pedestle and is blown dry with compressed air. From the bath until it is finished, it does not get touched by bare hands. Latex gloves are the norm for masking,painting, and decaling. Not until after the final seal coat do the gloves come off. Skin oils can make paint not stick to nothing,so don't let it wreck a paint job!!
 
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This is another one of those PC or Mac discussions with few in the middle. I rarely use primer, and when I do it's because I'm painting a light color over black plastic, (orange and yellow are the worst!) or because a customer requests it. When painting black plastic shells, I like to use plain old Testors silver, not the acrylic!) it's cheap, it covers with a very thin coat, and does not obscure detail.

As the gentleman said, it has to be clean! I'm lucky enough to have a blasting booth and a large ultrasonic cleaner. After those, a rinse and blow dry, then an overnight wait. Gloves when taking out of the ultrasonic, and after! It's what works best for you. My way works for me. You decide.

No primer used on any of these models:
MVC-011F.jpg


MVC-002F.jpg


DSCF0124.jpg
 
V&AL said:
First off a word about Krylon Fusion (the stuff made for plastic).

Put the can down gently and run away quickly.
Click to expand...

This is true of all spray paint.

I still occasionally use spraycans if I need to shoot a passenger car interior a base color, but never on anything that is going to be seen directly. Spraycans lay it on thick. Add that thickness to a primer, to factory paint, many details are going to be swallowed up.

Andy
 
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