To prime, or not to prime, that is the question

[Kaenned]

Hi guys

I paint with Tamiya TS spray paints, and have always used Tamiya primers as a foundation as I always assumed that is the best way to go. But recently I had a conversation with a mate, that said that you don't need to prime the plastic parts as long as they are the same colour. Does anyone know if its okay to skip primer? It would obviously make a lot more sense why Tamiya often produce the bodies in the same colour as on the box art, as it would take a lot less paint to cover, when the underlying material is the same colour.

[Nicholas]

i have done both, the only time it bit me in the a$$ was when the plastic had some swirls in it from when it was made,now a days i prime EVERYTHING, no reason not to, keep in mind you can get primer in white if you want to brighten up a base coat.

[64SS350]

Yes prime! One, it does help you find imperfections (as mentioned above), two, it puts a barrier between the paint and plastic if you need body work, three, the paint will adhere to the plastic, so if imperfections are present in the paint... stripping becomes challenging.

My two cents 

[yh70]

ever thing i have built i have primed..

[CaddyDaddy]

I'm not gonna comment on paint adhesion, etc....There's way better "chemists" on this board then I am. I will say that I prime every body I paint. Why? I'm a stickler for getting out any imperfection in the "sheet metal". I sand and spot putty, thinking I have everything up to snuff. I shoot a coat of gray primer, and magically, I can see everything I missed or boogered up. Would hate to take the time to lay on a nice paint job and then find these nicks, swirls or high and low spots.

[Rich Chernosky]

I rarely if ever prime under Tamiya. And I use a LOT of it.  Tamiya is made for plastic.  Try stripping Tamiya off plastic after it has cured (about 10 days)  if you are worried about adhesion. On another note you will get a higher shine with less coats if you paint Tamiya  over a smooth shiny surface. Prep work for me includes sanding down mold lines then shining the plastic back up, then a good scrub with a soft toothbrush and scouring powder to remove mold release and oils.  Most of my work is airbrushed so I don't have very heavy coats. 

[Michael jones]

I always prime the bodies with Tamiya primer, but other parts - only depending on the colour of the plastic and where it is on the model.

[Ace-Garageguy]

I primer everything, even small parts.

Mold lines that have been removed but aren't perfect and need more work show up better with a coat of primer.

Still, I see a lot of builders leave mold lines on just about everything.

But then again, I usually sweat the small stuff.

Edited May 31, 2024 by Ace-Garageguy

[slusher]

I prime every part that gets paint even brush painted!

[64SS350]

I realize you asked about painting on molded in color, but here's an example from several years ago. I decided to pull out a stalled project because of paint and decal issues. Tamiya paint, no primer, also some sanding.

 

[Dave G.]

Tamiya plastic is pretty good but for some kits, to the naked eye everything looks good for paint. You put down the first coat of paint and some swirl or other inconsistency in the plastic transfers through  paint and will show right up. Subsequent coats just magnify it all the more. One simple primer coat would have sealed that off. Or else shown it so work could be done. My answer is I prime all bare plastic that will show.

I also prime early on in a new build, simply because I don't like the look of bare plastic. A coat of primer also brings out the details of the parts, takes the glow of plastic away.

Edited May 31, 2024 by Dave G.

[peteski]

This question comes up here repeatedly, but since you only have 8 posts under your belt (and probably didn't do any forum searches) you wouldn't know that.

Here is one such thread from coupe of years ago. Same info will likely be repeated here.

 

[Rick L]

Come on guys, let’s stop with the redundant questions. It’s starting to piss Pete off.

[DJMar]

21 hours ago, Ace-Garageguy said:

I primer everything, even small parts.

Mold lines that have been removed but aren't perfect and need more work show up better with a coat of primer.

Still, I see a lot of builders leave mold lines on just about everything.

But then again, I usually sweat the small stuff.

I'm with you on this, 100%.

[peteski]

3 hours ago, Rick L said:

Come on guys, let’s stop with the redundant questions. It’s starting to piss Pete off.

Rick, I am well aware of you disdain for me, but what's wrong with mentioning that this is a well-covered subject, and actually pointing to the relevant info?  Is it really *THAT* bad? I am so sorry if you don't approve. I might have to notify the moderators that I have sinned.

[Ace-Garageguy]

27 minutes ago, peteski said:

...I might have to notify the moderators that I have sinned.

Just say 40 Hail Pactras and don't do it again.  

[Dave G.]

8 hours ago, Ace-Garageguy said:

Just say 40 Hail Pactras and don't do it again.  

Ahhh, Pactra, my favorite enamel back in the day !

[Rick L]

10 hours ago, peteski said:

Rick, I am well aware of you disdain for me, but what's wrong with mentioning that this is a well-covered subject, and actually pointing to the relevant info?  Is it really *THAT* bad? I am so sorry if you don't approve. I might have to notify the moderators that I have sinned.

 

[Rick L]

What’s wrong Peter is the fact that you have a condescending tone to many of your answers. 

[TNT]

I like to prime more than not. As mentioned above it helps to find blemishes. Also depending on the paint primer gives the paint something to bond to. With out primer a few sharp bumps may just take a chunk of paint off. In the warm weather i really like duplicolor and cooler weather badgers primer well it is sold under a name that starts style maybe like styliners or something like that. Also a good primer base will make brushed on paint look better too.

[Rocking Rodney Rat]

On 5/30/2024 at 9:03 PM, Ace-Garageguy said:

primer everything

Duplicolor DAP-1699 (sands better than DAP-1700) available at your local auto parts store... -RRR

[StevenGuthmiller]

I see this question bantered about on the Facebook groups all of the time.

Honestly, the lack of adequate and proper priming is probably responsible for nearly 50% of the botched paint jobs that I see there.

 

I'll just give the standard answer that I usually offer for this question.

There are a number of reasons why priming is good practice, which I won't get into here.

I'm sure that those reasons are pretty much known by all.

 

Priming is not just an excuse to use more paint, and is used in virtually every paint application universally, whether it be for 1:1 automobiles, your house, or anything else.

Any painter in the real world that is worth his salt is going to prime prior to paint, and the reasons for that are voluminous.

Whether or not you choose to extend that practice to a model is entirely up to the individual I suppose, but personally, I wouldn't even consider spraying color until adequate priming has been completed.

That goes for not only the body, but any other part of the model that is going to receive paint.

 

Let's just say that if you want your paint jobs to be consistently successful, it's just a very good habit to get into.

 

 

 

 

Steve

[bobss396]

I prime almost everything. Some small 3D printed parts are the exception. Even with handling after paint, the finish holds up.

As I get older, I don't see as well as I used to. Primer shows problem areas a lot better than no primer.