Mottles

When I paint mottling, I use a fine needle & tip (Badger 150), I thin the paint to almost 50:50, and spray at 5-7psi. very close to the model's surface. Here's a link to one I just finished (Bf 109K-4)http://finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=8238

wow pix, thatz a nice K4, and btw, thanks for the advice! But im guessing the paint dries almost immediatly?

If you don't have an airbrush, try this. Thin the paint with about 30 per cent thinners. find an old, thick brush. Cut the bristles down to about 10mm, dip into the paint, then remove most of it onto a rag. Apply the ends of the bristles to the model in short gentle stabbing movements (practice first!). This is called stippling & can be very effective. You can use various different sizes of brush, depending on how big you want the mottles.
If the paint dries too thick it can be rubbed down with very fine wetndry, this should not affect the appearance of the mottles too much.
As I say, it takes a bit of practice but can look very good.
Pete

Thanks, dadfad ! The paint does dry fairly quickly. I use Model Master II enamels, which are semi-gloss. Flat paint, and paint that is not thinned as much will dry quicker (as will acrylics). There is also the amount of paint applied. I usually get it in one coat (the mottling), as trying to go over it with another coat has not been very successful for me.
As albertsponson points out, it is wise indeed to practice first. Try it on scrap, an old kit, or the inside of a wing or fuselage that will not show later.
Good luck, & post the results when you're done !

you can use blue tack (silly putty) to make the dot pattern and then overspray

Well i tried mottling using MM acrly paints at 5-7 psi, but the paint starts to splatter. Any ideas?

Does it start to splatter immediately, or only once you've sprayed for a while ? If its the latter, you may have to keep cleaning the tip with a brush dipped in alcohol or the thinner that you're using. I do my mottling with enamels, so it may be a little different with acrylics. What are you using for an airbrush ? Is the tip in good shape ? (roll the needletip sideways on your fingertip to check for a slight bend) You may also want to try thinning the paint a little more.
Check the needle tip, and try slight variations with the paint/thinner mix, pressure, & distance from the model. One of these may correct your problem.
Good luck & have fun !

well its an iwata revolution CR, sort of new, and the paint splatters right when i push down for air.

I have that problem when I accidentally let off of the air before I let off of the paint. I've read over and over again that I shouldn't ever let off the air first, but sometimes I screw up and do it anyway. Take extra care to slide your trigger forward before you let it back up and I'd bet you won't have that problem again. Obviously, always begin and end your paint away from the model. Hope that helps, it solved that problem for me (really I just wasn't used to using a double action airbrush).

madda

spray with dot color, make a dot pattern using silly putty,spray with the base color
this gives hard edges, so a second weathering wash will blend the dots if yo want to do so.

There is an etched brass mottle stencil, I am not sure of the manufacturer.

I did a FW a while back and actually masked the whole model with pieces of Masking tape torn to small pieces leaving open the areas I was going to spray the spots to.
The rough edges from the torn masking tape gave a real nice mottled effect.