When applying a wash...

If the wash is water, you can't leave it on too long (few minutes). If the wash is enamal and you are rubbing it off iwth thinner, you an wait much longer. The future creates a barrier between your wash and the paint job.

Anthony - that's exactly right... and dont spray the Furture real thick, it's better to apply two or more coats until glossy because you'll end up with drips and runs otherwise... if that does happen, Future can be taken off with Windex.

If you are spraying over a dull coat of paint it might take more than one or two coats to get it glossy as it almost looks like the dull paint "drinks up" the future...

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I always put a coat of Future on after decaling and weathering to seal the decals... it works so good that it is almost impossible to even scrape off the decal after being futured over... then dull coat if needed on top of the future and you have a paint job and decals protected from nicks and aging!!

It's just a matter of trial and error. Put some on and wait a bit, then wipe off. If the wash comes out of the panel lines, just re-apply and wait a little longer the next time. Eventually you'll figure out how long you need to wait to get the effect that you're going for. And, as mentioned above, the Future will protect your paint job as you do it. You may also want to try putting a couple of drops of dish detergent into your wash to create what is called a 'sludge wash'. This will help to break the surface tension of the wash and help it adhere better.

Paul Boyer put his recipe in FSM a few years ago, and I think it is: three parts paint, five parts water, and a few drops of dish soap, such as Dawn. Hopefully a colleague here can clarify this.
Note: the dish soap changes the surface tension, making it easier to remove. I don't use any dish soap that moisturizers, etc., as that might interact with the pigments in the paint.

do u add dishsaop only to acryls? or will it work its magic with enamels aswell?

I've found you can only use flat acrylics with dish soap for the washes as when using glossy colours it turns into a big ball of playdough like substance!

Stuka, that's an excellent tip, that I did not know. I will definitely pay attention next time I make up a wash.

If your new to washes, I suggest you use watercolors for your wash.
mistakes come off easy and once sealed is as durable as acrylic or enamal.

I keep a package of Crayola watercolors for washes.
The come in a thick "paste" in a plastic tub pack, which comes in handy for mixing paint when empty.