The subject of primer

Yes, I have read the FAQ before I speak.
AF FAQ - What is primer? Do I have to use it? (http://www.automotiveforums.com/vbulletin/showthread.php?postid=578991#post578991)

I know everyone (or maybe 99%) is agreeable to the almost mandatory step of spraying a base coat or primer before putting on the actual body colour to the body of a model car. After I saw the satisfactory result of my first car kit primed before spraying & sanding, I also believe in priming.

But I still cannot help to think of these questions in my mind:

1. Tamiya Spray can instructions never tells me to prime:
On the instructions, it says about spraying from a certain distance, spray it in the open etc. But how come there is nothing to say you should prime? Now, even if these instructions are general in nature, I don't even see it coming in its catalog. There is nothing from Tamiya that says, "if you are painting plastic model kits, please spray a coat of Tamiya Primer before applying Tamiya Spray."

2. Tamiya Spray is for plastic and metal:
On the can itself, it has the words "for plastic or metal". Does it actually mean that barring any imperfections on the surface to be sprayed, the paint is designed to be sprayed directly onto metal or plastic without priming at all?

Take a look at the literature accompanying this link. It does suggest that there is no need to prime at all, doesn't it? :confused:
Tamiya Ferrari 360 Modena body kit (http://www.tamiya.com/english/products/24242modena_yellow/modena_yellow5.htm)

3. If considering that kits like Tamiya have a near perfect and smooth body kit, and I do not have to do any puttying or repairs, do I still need to prime? Take the Tamiya Honda Fit (Jazz) model kits for example, it is also released in different molded colours for the body kit. You have Taffeta White, Nighthawk Black Pearl, Iris Red Pearl etc. Well, if it is strongly recommended that we should prime before spraying the body colour, what's the point of offering these kits in different colours?

HLJ link -Tamiya Honda Fit (molded in Taffeta White) (http://www.hlj.com/cgi-perl/hljpage.cgi?TAM89590)

The only reasons I can see are:
a) Some kits no need to prime.
b) Kits are offered in colour for those who don't want to paint or just want to clear coat.
c) Some modelers just apply the body paint without priming and the result is no different from priming (barring any imperfections on the kit).

I do think this issue merits some discussion as I believe it is different from "to do panel line or not".

I appreciate if anyone can contribute their opinions. Thanks.

I've done a few paint jobs without primer and they didn't turn out too bad. However, the ones with primer all seem to be better. The risks are:
- the paint might 'craze' the plastic
- the paint might not stick to the plastic very well
- you might have a hard time getting good coverage wherever there is an 'edge'
- some plastic colors (red especially) can bleed through the paint. Imagine painting a body molded in red with a yellow paint, and then seeing the red start to show up through the paint.
- sometimes the color your using can be affected by the underlying color of the body. Painting yellow overtop of a red molded body is almost certain to show up a little 'orange'. Putting on primer gives you a neutral base coat so you will have confidence that the final color will be exactly what you want it to be.
- sometimes it's hard to get ALL of the little scratches and scuffs out of the body. Most primers will gently fill in these little imperfections. This is good because then they don't show up when you put on the final paint color.

All of these are 'maybes' that you never really know the answer to. If you absolutely know that none of these things will happen, then go ahead and paint without primer. If your not sure, then best be safe and deliver a nice smooth coat of primer as a little insurance policy against the above.

There's surely other reasons, but I'll leave it with that and see what everyone else says.

Murray

The reason I would prime a model is if I did some heavy sanding or bodywork. I use the primer to show me where I need to sand some more or else end up with a crappy paint job. I feel that the primer is better to use for this than a base coat of paint, mainly because you can easily respray a small area of primer and it will blend in with the rest. Not so easy with paint, but it can be done. If I do end up needing to sand again then to me the primer sands better than paint and the primer also dries to a sandable stage quicker than the paint.

Originally posted by shieldwulf
Yes, I have read the FAQ before I speak.
AF FAQ - What is primer? Do I have to use it? (http://www.automotiveforums.com/vbulletin/showthread.php?postid=578991#post578991)

I know everyone (or maybe 99%) is agreeable to the almost mandatory step of spraying a base coat or primer before putting on the actual body colour to the body of a model car. After I saw the satisfactory result of my first car kit primed before spraying & sanding, I also believe in priming.

But I still cannot help to think of these questions in my mind:

1. Tamiya Spray can instructions never tells me to prime:
On the instructions, it says about spraying from a certain distance, spray it in the open etc. But how come there is nothing to say you should prime? Now, even if these instructions are general in nature, I don't even see it coming in its catalog. There is nothing from Tamiya that says, "if you are painting plastic model kits, please spray a coat of Tamiya Primer before applying Tamiya Spray."

2. Tamiya Spray is for plastic and metal:
On the can itself, it has the words "for plastic or metal". Does it actually mean that barring any imperfections on the surface to be sprayed, the paint is designed to be sprayed directly onto metal or plastic without priming at all?

Take a look at the literature accompanying this link. It does suggest that there is no need to prime at all, doesn't it? :confused:
Tamiya Ferrari 360 Modena body kit (http://www.tamiya.com/english/products/24242modena_yellow/modena_yellow5.htm)

3. If considering that kits like Tamiya have a near perfect and smooth body kit, and I do not have to do any puttying or repairs, do I still need to prime? Take the Tamiya Honda Fit (Jazz) model kits for example, it is also released in different molded colours for the body kit. You have Taffeta White, Nighthawk Black Pearl, Iris Red Pearl etc. Well, if it is strongly recommended that we should prime before spraying the body colour, what's the point of offering these kits in different colours?

HLJ link -Tamiya Honda Fit (molded in Taffeta White) (http://www.hlj.com/cgi-perl/hljpage.cgi?TAM89590)

The only reasons I can see are:
a) Some kits no need to prime.
b) Kits are offered in colour for those who don't want to paint or just want to clear coat.
c) Some modelers just apply the body paint without priming and the result is no different from priming (barring any imperfections on the kit).

I do think this issue merits some discussion as I believe it is different from "to do panel line or not".

I appreciate if anyone can contribute their opinions. Thanks.



Tamiya instructions don't mention a lot of things necessary to make a good model, like removing mold lines, filling ejector pin holes, etc. But they are of course necessary if you want a perfect model, just as priming is almost crucial to getting a good paintjob. That's why Tamiya sells a Fine White Primer and a Gray Primer. One reason perhaps is that it might discourage people from buying Tamiya sprays if they find out they have to buy the Tamiya primer with it. :)

The Honda Fit Jazz thats been released in so many colors is for weekend modelers who more often than not just glue everything together and don't paint.

Even if a body comes 'perfectly' molded straight from Tamiya you still need to sand off the mold lines, which introduces scratches onto the body that need to be filled up with primer or may show through to your final color coat.

Hope this answers some questions :)

Many of the Tamiya TS paints are semi transparent, so if you are spraying over a darker plastic or color other than the paint you are spraying, you will end up with a strange muted/darkened color. When in doubt prime with white primer, you can't go wrong. :)

If you want a plastic looking see through model don't prime. If on the other hand you want a solid realistic looking model prime it. I don't understand this big fear of primer. Prime it!!!!!!!!!!!!!! and stop looking for excuses not to.

Originally posted by 935k3
...I don't understand this big fear of primer. Prime it!!!!!!!!!!!!!! and stop looking for excuses not to.
Fear? :rolleyes:

Well from my experience i use to do models with no primer at all and the models still come out very nice providing that the body is nicely made like by tamiya.
But i foudn some problem with no primer
- colour of the kits will mix with the paint you spray on so there will be a colour chnage
- the plastic feel cause light can just go through it
- if you made any mistake when you sprayed very likely you can't fix it cause the spray usually kills the plastic :(

and primer what more can i say it is so very very useful

but yeah if you are lazy and not planing to spend too much time no primer is still ok... i mean its your model so do what ever you like as long as you enjoy it

but personally i like using primer :P