Woodworker's Journal 2011-35-Winter, страница 27
If you scrape some settled pigment from the bottom of a can, you can see what it looks like when congealed. off. The type of wood and how finely you sand it both have a great impact on how much pigment stain will lodge in it. In short, the more pigment you leave on or in the wood, the more color you get. To some degree, you can intentionally leave more sitting atop the wood, but that has its downside, as we'll see. What's in Pigment Stains? Remember our piece of wood graced with mud? Once the water evaporates, we could easily brush the dry dirt back off the wood, but you can't brush real pigment stains off wood so easily. The reason is that in addition to the pigment and the solvent (dirt and water, in our case), commercial pigment stains contain a third ingredient. The third ingredient is called a "binder," and it is some type of finish that acts like a glue to make the bits of ground-colored dirt stick to the wood. The binder can be anything that dries to form a film capable of holding pigment, and also capable of sticking to wood. Most stains use linseed oil or oil-modified resin as the binder, while pigmented water-based stains usually use acrylic resin. Artist's oils and artist acrylic colors work the same way. They contain high concentrations of pigments mixed with either linseed oil, soy oil or acrylic resins. If you add mineral spirits to the oil colors or water to the acrylics, you will have made pigmented stain from common art supplies. Japan colors, which are merely artist oils with driers added, work the same way, while universal tinting colors work much like acrylics, but they will mix with both water- and oil-based solvents. If you are inclined to mix your own pigmented stains from scratch, these are some materials you can use. The Dirty Little Secret Now we know that there are three basic elements in pigmented stains: solvent, pigment and binder. Quick, tell me what are the three basic elements in a can of paint? If you said "solvent, pigment and binder," you are correct. So, what is the difference between paint and pigmented stain? Mostly the percentages of each of the ingredients. Stain has more solvent, and may have less binder or pigment, depending on the particular stain. Want proof? Take some paint, preferably a color you would choose as a wood stain, and dilute it 50/50 with solvent; water for latex, mineral spirits for oil-based paint. Wipe or brush it onto a piece of wood, then wipe it off and it will look like a stained piece of wood. In fact, that's a great tip for those times when you can't find just the right color stain and you don't want to mix it yourself. Choose the right color paint chip from that endless wall of color options, take it to the paint counter and have them make up a quart of custom colored paint in either latex or oil. Take it home and thin some out and you have the perfect color stain with no mixing required. If You Know Paint, You Know Stain Everything you know about paint applies to pigmented stains as well. If you put on a thin coat of paint (stain), whatever is beneath it, including the wood grain, will show up. Once the paint (stain) is dry, you can put on a second coat if you care to make it darker, but the more you put on, the more the grain will be obscured. You can apply the paint (stain) in thinner or thicker coats, but if you put it on too thick you might incur much longer drying time before you can recoat. Since pigmented stain reacts differently depending on how the wood is sanded, it is vital continues on page 28... > Staining softer summer wood can create a "photo-negative" effect. winter 2011 27 |
