The modeling gods probably don't like me very much...

[GU-11]

And now we move on to problems with primer.

I just noticed that Tamiya also sells a "fine" surface primer, along with its regular primer. The regular ones have a rather grainy finish, and I have to wet sand the parts to get a smoother finish. Thing is, I've already bought three cans of the regular stuff before realizing there's another version.

Honestly, I'm not sure if this has to do with the humidity in the air or the primer itself.

Can anyone give any advice on the difference between the "fine" surface primer and the regular stuff?

Or is the grainy finish due to the weather and spraying distance?

[Cesar Enrique]

As far as I know, everything has to do with the quantity of thinner used, the same applies on acrilyc paints, if you use fewer thinner than paint, it will result on a grainy finish.

Also, I have read that spray primers and paints are a wrong way to obtain fine and smooth finishes, in youtube you can find videos of a japanese guy that "milk" (or extract) the primer from the spray can into a bootle, then use some thinner, and then apply the mix with airbrush.

[EXO]

By regular stuff do you mean primer in a can? There are primers that have extra grit that needs to be sanded down before you apply paint. It's called filling primer. You don' really need it unless your surface is uneven. It's thick so it can fill up surfaces that are sunk and then you can sand it smooth. Usually it's needs a couple of coats before it becomes even. You use it if the unevenness is not enough for putty but too much for surface primers.

Just use the Tamiya Fine Surface spray if you can. It's probably the only primer you need if you're just prepping for your Tamiya color paint.

[GU-11]

Thanks for the info, guys!

@ EXO: Is there any way I can still use the regular surface primer cans for prepping a kit's surface before painting? These things are expensive, and I actually brought three cans of it.

@ Cesar: I heard that you need to use lacquer thinner to thin Tamiya primer, and acrylic thinner won't work with it. Can I use regular industrial lacquer thinner you get from hardware stores, instead of Tamiya's branded lacquer thinner? The Tamiya store is pretty far from where I stay.

EDIT: I've heard that Future Floor Polish makes a decent primer for acrylic paint. Is that true? I've got a bottle of it at home.

If so, I might just use that, and save the Tamiya Surface Primers for when I need them, i.e. uneven or scratched surfaces.

Edited October 5, 2012 by GU-11

[vt102]

Hi. As far as future goes... I never heard of it being used as a primer?? They are great for clear canopies, or I even heard of people using them as a clear top coat... but not a primer.

[EXO]

Are they really that grainy? Is it humid or really hot where you are at? Sometimes the heat causes thicker paint and primers to dry in mid-air and create a gritty surface. Maybe you should practice holding the can closer to a test surface.

Also, you can always save those cans for later. Once you do a lot of painting you're going to understand when you need that type of primer. You just need the experience to know when to use what material. But if you must use them, then you have to sand if they really are that gritty.

[GU-11]

Are they really that grainy? Is it humid or really hot where you are at? Sometimes the heat causes thicker paint and primers to dry in mid-air and create a gritty surface. Maybe you should practice holding the can closer to a test surface.

Also, you can always save those cans for later. Once you do a lot of painting you're going to understand when you need that type of primer. You just need the experience to know when to use what material. But if you must use them, then you have to sand if they really are that gritty.

Now that you mentioned it, heat and distance could be a possible cause. I tried to spray as far away as I could to prevent coating the parts in too much primer. And the heat where I'm at can get atrocious sometimes, especially outdoors. I've finally got a spray booth, though, and I'm planning to move my painting indoors.

BTW, can I use flat clear spray as primer for surface prepping? I was thinking maybe the matte coat might give enough tooth to the surface for better adherence, although not as good as proper primer. The reason I'm trying to hold off on buying that fine surface primer is because I'm already using more money than I should right now, and I'd like to save up whenever I can. And since I've got an extra can of flat clear spray, I just thought I'd use that as a possible alternative.

Or maybe I should just go without the primer? I plan on coating the kit in Future Floor Polish anyway, which protects the paint in a clear, rock-hard shell. Would that be sufficient to prevent flaking and chipping?

Hi. As far as future goes... I never heard of it being used as a primer?? They are great for clear canopies, or I even heard of people using them as a clear top coat... but not a primer.

Thanks for the confirmation, vt102. I read some posts about it using FFP as primer, but I guess it's probably just some untested theory.

[vt102]

Sounds like you might be a tad too far away. I have not used the regular Tamiya primer, but it must be similar to regular non hobby type ones. I used to use my local auto store brand primer on my car kits... it went on pretty good, but could be smoother. I just bought a can of the Tamiya fine, and it does lay smoother than my local auto store one. But you could also sand the regular primer, to smooth it out a little....

[GU-11]

Sounds like you might be a tad too far away. I have not used the regular Tamiya primer, but it must be similar to regular non hobby type ones. I used to use my local auto store brand primer on my car kits... it went on pretty good, but could be smoother. I just bought a can of the Tamiya fine, and it does lay smoother than my local auto store one. But you could also sand the regular primer, to smooth it out a little....

To be honest, I don't mind doing a little more work wet sanding the parts. But what I'm most worried about is that the primer might fill up all the panel lines and details--for example, those "energy lines" on Kotobukiya's ZOE Jehuty model kit.

Also, I came across this problem when sanding the sword blades of my MG Gundam Exia. As the primer was a little too grainy to get a smooth coat of paint, I wet sanded the blades, and inevitably sanded off a bit of primer from the blade edges, leaving naked plastic. Maybe this has more to do with my poor sanding skills, though.

Hopefully, it is as you and EXO said, and it's just the heat and my spraying the primer at too big a distance (about less than a foot away, if I remember correctly). I'll give it another try next week and see how it goes.

If not, I might have to try other alternatives like using flat coat as a primer to give the surface more tooth.

[shdwfx2000]

I wouldn't imagine Future being a good primer. I think of it like this, you would primer wood or porous surfaces to keep from having to continually dump loads of paint on it as it would wick it away, the primer would also afford some measure of a moisture barrier. With plastics, primer gives a model tooth, like was said previously, the desired coat of paint can adhere better to the primer because on the smallest level, the primer is rougher then the slick plastic would be. If you were using enamel on plastic or lacquer you could skip priming because the thinner in both melts the surface of the plastic just enough for the paint and plastic to bond. Any primer based paint will do that. Try spraying styrofoam with thinner based paint and you'll see what I mean. (don't do it on something important, it'll melt it).

Now I paint most of my figure models in acrylics. Acrylic is mostly water based (like Future) with suspended pigments of plastic. They work like glue, it goes on, makes a surface tension and sticks. But you can scratch that off pretty easy.When you scratch it it comes off in sheets sometimes. It just sits on the surface. Future makes for one hellova top coat (if you want glossy) but as primer, either your thinner based paints will melt through it, making it pointless for priming or with acrylics, just another delicate surface treatment.

Think about it like this, if you spilled acrylic paint on a floor covered in it, you could just wipe the paint up.

If you spray painted the floor, you aren't wiping it up.

Also, as was said above, it does sound like it's either too hot to paint where you are, or your too far from the model when spraying, the thinner is evaporating before getting to the model and all your left with is the pigment. A little closer with nice even sprays and you should be good to go.

Edited October 5, 2012 by shdwfx2000

[Phyrox]

I use the widely available "surface primer for plastic an metal (grey)" by Tamiya, and I love it. A minute or so with the can and the model looks like it was molded in flat grey. I have never had any problems with it.

[Jasonc]

Worst places to paint, are in extremely hot, and humid places, especially if you're going for a fine finish. In hot days, either do it in early morning, or towards the evening. Mid 70s is a good temp and low humidity will usually produce good results. At worst case, lightly sand your primed areas, and clean out the panel lines. 9 times out of 10, things can be corrected when they don't go right the first time.

[GU-11]

Thanks for all the input!

By the sound of it, it's most probably my own fault for spraying on a hot day; to make matters worse, it had rained the night before, although it was pretty warm throughout the next day.

I'll give it another try next week. This time, it'll be indoors, at a 10cm distance.

One more thing: should I warm up the can in hot water like most customizers recommend?

[MechTech]

^{10cm is good. Most cans say something like a whole foot, and that's waaaay too far away anytime I've tried it. Warming the paint can help sometimes, but I find no difference unless the paint is REALLY cold. Room temperature seems to be the same as "warmed" temperature. Most of my large paint jobs are spray paint canned based. Hope that helps! - MT}

[GU-11]

Thanks for the heads up, Mechtech!

Where I'm at, there's no chance of the paint being too cold (smoldering tropical country), so I guess there's no need for warming the can.