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I started this hobby at the end of last summer, and the only spray primer I've used is Armory's black. I didn't know what I was doing, and I only really did a few models with it before the weather got too crappy, but it seemed okay.
So I found an article about using Gesso as a primer for miniatures, and that sounded awesome since I would be able to prime models under any conditions. I picked up small bottles of Liquitex black and Liquitex white gesso from Michael's; up to this point, I've only used the black on metal models (Plaguebeaerers of Chaos Daemons), with great success. I loved this stuff, as I was able to apply it pretty liberally without worrying about brush strokes, since the stuff basically "shrinks up" to a smooth finish on your model
Last week I decided I wanted to try to paint some Space Marines, and I thought I'd give the white gesso a try. For some reason though, it didn't behave the same way as the black gesso did. It didn't shrink to the model nearly as well, which resulted in some unsightly brush stroke marks and a Simple Green bath for the test Marine. I tried again with a thinned mix of gesso and still didn't really get good results.
So I'm wondering if anyone with experience can help determine if the white and black gesso actually do behave differently, or if it's more to do with the models (since these are plastic, smooth Space Marines as opposed to metal, detailed Plaguebearers). After the holidays, I'd also be willing to try these prime jobs over, take pictures and post them to see what y'all think.
I have never tried Gesso, but could it have anything to do witht he climate. I find that when I spray prime during the winter I get poor results when it is most cold. One thing you may wish to try if you are into spray priming is Army Painters spray primer. I have fell in love with the stuff. I don't use the dip but I have able to pump out decent looking marines in minutes.
I did some experiments with white gesso last winter and didn't have any problems. I was using standard plastic Guardsmen and tried gesso straight from the jar and also watered down. Maybe it's the brand you're using?
Did you find that the thinned or unthinned worked better? How much did you thin (like a quarter water)? Also, which brand did you try?
I'm not really sure why it's not working for me... I'd read about people having success with the Liquitex stuff, and like I said, the black worked really well. For the Space Marines, as I paint it on to the smooth armor plates like shoulder pads and backs of legs, I can't really control how much gesso goes on and as I try to smooth it out, it leaves brush strokes which end up showing in the finish. I'm also a noob so I don't really know what I'm doing.
I guess I'll try the black on a Space Marine and see how it works, just for comparison's sake.
I use both as well and don't really notice a difference. Liquitex too. The only time I would add more water than painting with a soggy brush would be for a little smoothing coat if the first layer got a bit too splotchy.
Could it be your brush? have you tried using different ones? I mostly use round brushes or an old GW drybrush for it and don't get problems.
White gesso does not act the same as black gesso- I've discovered this through trial and error. White gesso needs to be watered down in order to get a good effect, but once you water it down you no longer get a smooth basecoat. So I would recommend ditching gesso if you need a model primed white, because it really isn't going to work out well.
That said, if you mix white gesso with black craft paint and thin it down, the results are fantastic. Excellent coverage, excellent tooth, shrinks right down.
If you think Mathammer doesn't work and dice cannot be predicted, there's a whole field of mathematics called probability that would like to disagree.
Never tried Gesso -to be honest I get on fine with sprays. I did have a few problems with the varnish in winter once but I have a solution that works for me:
It's too cold for the cans and the propellant gets all 'clumpy' - the solution is to keep the cans inside in the warm (and shake them well inside while they're warm). Prepare your spraying area (for me, in the shed out back where it's about 0 degrees right now) - then run outside, spray the model(s) *lightly* and quickly from 12" away, resist the urge to go over what you've already sprayed then turn the can upside down and clear the nozzle. Now take the can and the wet model inside to dry. The last bit is important I think - models don't dry well in the cold. Repeat the process as necessary (with the army painter sprays this is usually one or two coats - citadel takes maybe 3).
Note: I usually mount the model onto something I can man-handle with blu-tac to avoid having to touch the model itself when moving it around and I usually cover it while it's drying with a big vase upside down or something -to avoid getting dust and hair on it.