So, in order to solve these problem a number of steps are involved to regulate the color and build the color in layers to achieve the final result. Different colors a effects will take different approaches, but this one is a pretty typical approach.
First, eliminate dust. This is critical element in producing a quality finish and I spend about an hour prepping the shop. The thing to remember is that moving tools around puts dust in the air, so moving things is the first step, vacuuming is the last step, after the airborne dust has had time to settle. I use a cyclone vacuum with a HEPA filter to reduce the amount of dust blown back out into the air.
Then each item to be stained is carefully vacuumed with a brush attachment. I like this better than blowing compressed air because it reduces airborne dust which can settle back onto the pieces.
Now you're ready to begin.
1. Wash coat. This is a highly diluted sanding sealer (5% solids by volume) which partially seal the wood pores. This takes advantage of the uneven absorption rate of the wood. More absorbent areas suck up more sealer, thus reducing the difference of absorption between areas.
The wash coat in this case is water based, as is the dye stain, which will cause the grain to become "raised." meaning it will feel rough again, even though it's been sanded smooth. So, now it has to be resanded, lightly to smooth it out again but not enough to cut through the wash coat. Once over with a fine grit sanding sponge, using minimal pressure is usually enough. Vacuum again before continuing. After this first grain raising, it shouldn't happen anymore.
2. Dye Stain. Dye stains produce much darker colors than typical pigment stains, and are easier to control because they can be more easily thinned out or removed. But they aren't readily available and usually have to be custom blended. I spray a light coat of the stain as the first color layer. Using the spray gun I can selectively darken lighter areas to even out the overall color of the piece.
Second Wash Coat. While having the same effect as the first coat, this second coat also seals the dye stain. Dye stains usually respond to a large number of thinners (from water to alcohol to lacquer thinner and more), so to prevent the second stain from interacting with the dye, this coat seals the dye stain. This coat also further seals the wood grain, so the next stain will apply very uniformly.
Oil Stain. Now the second layer of stain is applied. This one is oil based, using pigments. It will produce a nice uniform color and add depth. This is sprayed on lighty then wiped off to reveal the grain underneath. If the wash coat hadn't been applied before hand, this wiping might have removed some of the dye stain as well.
Sanding sealer. This is a coat of sealer with a lubricant added. It makes sanding easier and faster. One coat is usually enough. After it has dried, it is lightly sanded and vacuumed to smooth out any remaining rough spots in the finish. If you've kept the dust down up until now, the effort will really pay off.
Top coat. This is the final hard coat which will provide a durable surface. I usually use 2 coats, but more may be needed depending on what finish is used (check the label, too much can lead to finish problems) If you've done all the sanding and vacuuming up till now, you shouldn't need to do any for the top coat. Your finish should be smooth.
When applying the sealers and top coats, it's critical to not apply too much. I use a carefully adjusted spray system and mil-gauge along with the manufacturer's recommendations. And I always experiment with new coatings before using them on a project. Make sure you have your system figured out before committing.
This last photo show the difference between using a strait oil stain (right) and using a combination of dye and oil stain (left). Both are pieces of maple from the same board, and both use the same oil stain from the same can. Obviously, the addition of the dye stain makes a huge impact on the final result.
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