Need Advice on Primer Sprays

[GU-11]

I finally decided to redo old model kit I did as a kid, and this time, I planned to do it right, primer, paint, top coat and all.

Now I've never used primer before, and the first time I used it on the kit today, it left a rather grainy finish. Is primer supposed to be like this? I thought of sanding the surface to make it smoother, but I was worried that if it were too smooth, it might not have enough "teeth" to hold the color paint, which is silver.

On the other hand, the graininess might cause the color paint to take on grainy finish as well.

In short: is the graininess normal for primed surfaces [in which case I should leave it alone], or would it be a good idea to lightly sand it down?

Thanks for any advice.

[Noyhauser]

I finally decided to redo old model kit I did as a kid, and this time, I planned to do it right, primer, paint, top coat and all.

Now I've never used primer before, and the first time I used it on the kit today, it left a rather grainy finish. Is primer supposed to be like this? I thought of sanding the surface to make it smoother, but I was worried that if it were too smooth, it might not have enough "teeth" to hold the color paint, which is silver.

On the other hand, the graininess might cause the color paint to take on grainy finish as well.

In short: is the graininess normal for primed surfaces [in which case I should leave it alone], or would it be a good idea to lightly sand it down?

Thanks for any advice.

Well for starters you will need a glossy surface for a silver; rough surface under the silver will not come out well. Its tough to say if the primer worked as advertised. What brand was it? Smoothness doesn't really affect the bite of a paint. It really depends what sort of finish you want, and what paints you're using. However in this case gloss is what you want.

[GU-11]

Well for starters you will need a glossy surface for a silver; rough surface under the silver will not come out well. Its tough to say if the primer worked as advertised. What brand was it? Smoothness doesn't really affect the bite of a paint. It really depends what sort of finish you want, and what paints you're using. However in this case gloss is what you want.

Thanks for the quick reply! I'm using Tamiya Surface Primer for Plastic and Metal [Gray]. For the color coat, it's Mr. Color #8 Silver Metallic.

As for the finish I'm looking for, I want the finish to be more like polished armor.

In any case, should I just sand down the primer or completely sand it off and spray a gloss coat on it?

Edited September 8, 2011 by GU-11

[Noyhauser]

Hmm, I've never had that problem with the Gray primer... maybe its a new bottle or a bad one but its one of my favorite products.

At this point all you can do is sand it down. Getting it smooth is good enough... you don't need another gloss coat. For future reference, you wouldn't necessarily need a primer coat under the gunze silver metallic. Its an enamel and is strong enough to sit as primer coat of its own.

Edited September 8, 2011 by Noyhauser

[GU-11]

Again, thanks for the advice.

I can't thank you enough for the heads-up on the gunze silver paint. The only reason I applied the primer was because I was worried that the silver might rub off or chip on naked plastic.

In retrospect, I think it might have something to do with the fact that it rained in the middle of the night. I slept right through it, and only found out from my neighbor just now.

I guess that rules out improper spray can preparations--I'd properly prepped the primer by soaking the can in warm water for several minutes, kept a 30cm spraying distance, applied thin coats and waited several minutes for it to dry between coats, and even swirled the can instead of shaking it.

Edited September 8, 2011 by GU-11

[anime52k8]

I tend to advocate proper surface prep and surface primer for everything you do. With metallic paints, I still use primer but then I also do a layer of gloss black for a richer, more reflective finish.

[GU-11]

I tend to advocate proper surface prep and surface primer for everything you do. With metallic paints, I still use primer but then I also do a layer of gloss black for a richer, more reflective finish.

Good advice, anime52k8. I'm a stickler for prep work myself, although in this case, I got "punked" by the weather.

Thanks for the heads up on the black spray. I did plan on that, but the hobby store's sold out of Mr. Color black for a while now. Could I use Tamiya's TS spray cans with Gunze Silver?

BTW, would light sanding be a good alternative to priming? Where I'm at, it rains a lot, and it can get aggravating if you have to wait for days on end for a temperate sunny day to do some spraying.

Also, how long do you usually wait between coats?

[anime52k8]

Good advice, anime52k8. I'm a stickler for prep work myself, although in this case, I got "punked" by the weather.

yeah, some things you just can't avoid.

Thanks for the heads up on the black spray. I did plan on that, but the hobby store's sold out of Mr. Color black for a while now. Could I use Tamiya's TS spray cans with Gunze Silver?

As a base coat for the silver, yes. Tamiya TS spray paint is lacquer based, so once it's dried and cured it's safe to spray enamels over it. Just don't try to put the Tamiya paint on top of the Gunze paint.

BTW, would light sanding be a good alternative to priming? Where I'm at, it rains a lot, and it can get aggravating if you have to wait for days on end for a temperate sunny day to do some spraying.

generally I do both but in situations where I couldn't use primer I've found just sanding and washing to be good enough.

Also, how long do you usually wait between coats?

depends on the paint and which coats your doing. for lacquer on lacquer about 24 hours (i.e. base color over primer). for acrylics or enamels over lacquer, a couple days. and anything over enamel, 3~5 days or more.

:edit:

oh yeah, also here's some important safety stuff. always spray paint either outdoors or in a well ventilated room and if you're spraying enamels or Lacquers, get a respirator. Not a dust mask; a full nose and mouth, air tight respirator that's approved for organic vapors. You can get them for $25~$30 and they are WORTH IT.

Edited September 8, 2011 by anime52k8

[derex3592]

I'd like to add here that I only recentley started using primers on models.. I started with Tamiya Fine Surface Primer and that was GREAT. Now it is literally IMPOSSIBLE to find. I switched to the generic $3 ish a can stuff at Home Depot and have NOT been impressed at all. It makes the model rough to the touch and now I am thinking of just not using anything anymore.

[Dobber]

I know, I feel your pain. Totally jealous that he can get Tamiya fine surface primer.

Chris

[anime52k8]

I have no idea what the hell happened within the last year or so to make Tamiya surface primer so scarce. I can still get it at my local shop sometimes but It's pretty inconsistent.

[Dobber]

It has to do with the labeling and California state law. I think the warnings and such on the label have to in english, or something like that.

Chris

[EXO]

labeling and now the earthquake made all tamiya products scarce. I've switched to an automotive primer sealer but there's nothing like good ol' tamiya. I'm also considering switching to adhesion promoters instead, but havent had the chance to mess with that. I know with resin and some plastics Tamiya sticks on without primer.

[GU-11]

As a base coat for the silver, yes. Tamiya TS spray paint is lacquer based, so once it's dried and cured it's safe to spray enamels over it. Just don't try to put the Tamiya paint on top of the Gunze paint.

Thanks. That's good news, as the place where I get my GS paints is a lot further than where I stock up on Tamiya stuff.

generally I do both but in situations where I couldn't use primer I've found just sanding and washing to be good enough.

Cool! That'll save me a ton of time.

depends on the paint and which coats your doing. for lacquer on lacquer about 24 hours (i.e. base color over primer). for acrylics or enamels over lacquer, a couple days. and anything over enamel, 3~5 days or more.

Wow, I'm glad I asked. I used to only wait for an hour or two [dry to the touch] before applying the next coat. The way things look, it'll take me a few weeks to finish this model kit.

oh yeah, also here's some important safety stuff. always spray paint either outdoors or in a well ventilated room and if you're spraying enamels or Lacquers, get a respirator. Not a dust mask; a full nose and mouth, air tight respirator that's approved for organic vapors. You can get them for $25~$30 and they are WORTH IT.

I've been searching to the fricking ends of the earth for a respirator, but just couldn't find one. Ace hardware, Home Depot [called Houz Depot where I'm at], and all the local hardware stores...none of them carry respirators. I had to make do with a double layer of surgical masks, topped with a NIOSH N95, and hold my breath whenever I spray. I do all my spraying outdoors, and walk to the other side of the patio between sprays.

It might or might not be enough, but it's the best I can do until I find a place that sells respirators. Wonder if I could order one online?

I know, I feel your pain. Totally jealous that he can get Tamiya fine surface primer.

Chris

One of the good things about being in Asia is that modeling tools and accessories are relatively easier to find. The down side is that the weather sucks donkey balls; it's usually either too hot or too wet to paint outside. A day of temperate weather is more the exception rather than the norm.

labeling and now the earthquake made all tamiya products scarce. I've switched to an automotive primer sealer but there's nothing like good ol' tamiya. I'm also considering switching to adhesion promoters instead, but havent had the chance to mess with that. I know with resin and some plastics Tamiya sticks on without primer.

Even Tamiya acrylics? I know acrylics are super fragile, but if they can stand up to reasonable handling, I might be able to save up on clear coats.

Edited September 9, 2011 by GU-11

[EXO]

acrilic on plastic scratched off. But on resin I really had to dig my nail in there and it eventually scratched off. More porous I guess.

[GU-11]

acrilic on plastic scratched off. But on resin I really had to dig my nail in there and it eventually scratched off. More porous I guess.

Thanks, EXO. I guess you just can't cut corners in certain areas.

[Jefuemon]

Ever thought about trying Mr. Surfacer? I use Mr. S 1000 as a primer, and really like it. Dilute it about 50:50 with Mr. Thinner, and run it through your airbrush.

[Noyhauser]

Wow, I'm glad I asked. I used to only wait for an hour or two [dry to the touch] before applying the next coat. The way things look, it'll take me a few weeks to finish this model kit.

Actually the Tamiya primer is an exception. I actually use it almost primarily because it dries quickly and provides a great base for doing follow on coats of lacquer alclad on small parts (like exhaust vents). Give it three hours and its good to go.

[GU-11]

Ever thought about trying Mr. Surfacer? I use Mr. S 1000 as a primer, and really like it. Dilute it about 50:50 with Mr. Thinner, and run it through your airbrush.

Thanks for the recommendation, Jefuemon. I can get a hold of Mr. Surfacer, but I don't currently own an airbrush. Planning on investing in one, but it'll be a while yet before I can set aside the cash for it. Honestly, I'm not even all that experienced with spray cans. Not sure if I'm experienced enough to handle the complexities of an airbrush.

Actually the Tamiya primer is an exception. I actually use it almost primarily because it dries quickly and provides a great base for doing follow on coats of lacquer alclad on small parts (like exhaust vents). Give it three hours and its good to go.

Thanks for the info.

BTW, I'd just wet sanded the parts today, and some of the edges were slightly worn off. Will this affect the final finish adversely? It's very slight, but I'm worried that the edges might chip. Then again, you did mention that enamel hold pretty well on naked plastic.

Think I should touch up with a couple more light coats or just go ahead and spray on the color coats?

Also, I have a problem with coverage when spraying primer. I can't completely cover the edges on sharp parts if I spray at a 20 to 30 cm distance. I can only cover the areas if I spray up close. Am I doing something wrong, or is it okay so spray up close?