Finishing Touch: Dye Stains
In an earlier article (Feb/Mar 2018) we looked at pigment stains, which are by far the most popular colourant woodworker’s use when they want to colour wood. While some of these stains consist only of pigment, many also contain a mixture of pigment and dye. Regardless, in both formats the pigments are suspended in a binder that bonds the pigments to the wood surface, while a carrier spreads the pigment and binder over the wood surface. A key aspect of these stains is that the blend of pigment and binder remains on the surface of wood, lodged in pores and surface scratches.
A stain consisting solely of dye, however, is quite a different type of colourant.
Two Types of Dyes
Powder dyes (above) are a little trickier to work with, as they need to be mixed and allowed to cool down before using. Liquid dyes (below) can be a bit easier and quicker to work with.
Measuring and Mixing
Here, Duguay mixes a measured amount of liquid dye into water. By measuring how much dye he adds, he can recreate the same colour down the road. Because he’s mixing the liquid dye with water he will have to apply a light coat of water to the surface of his project to raise the grain, then sand it smooth before applying the dye stain.
This sample of white ash was coated with one application of a dye stain on its surface, then when dry, Duguay applied a second layer of dye stain to the right half of the sample, leaving a much darker look. Finally, strain the mixture through a cone mesh paint strainer to remove any tiny clumps or bits of undissolved dye.
A dye is a soluble microscopic chemical substance that dissolves in a liquid. Once dissolved, the dye molecules remain suspended in the liquid and don’t settle out. Dye molecules penetrate deeper into the wood structure than pigments, without needing a binder to bond them in place. And, because dyes are translucent (semi-transparent) they don’t obscure the wood grain or muddy it up, which enhances the depth of the finish. The absence of a binder means that each application of the dye will blend into the previous coat, deepening the colour. Of course, as with a pigment stain, you still need to add a topcoat over the dye stain.
While pigment stains are colourfast, dye stains will fade somewhat over time, more so if subject to direct sunlight. Water-based dye stains are more fade resistant than alcohol-based dyes. In all cases, you don’t want to use dyes on outdoor projects.
Types of dyes
Virtually all the dyes that woodworkers use today are synthetic dyes, often referred to as ‘aniline dyes’. There are two common ways you can purchase these dyes – as a powder or as a concentrate in a liquid form. The powdered dyes we mention below are mixed with water – however, some powder dyes are oil soluble.
Concentrated dyes have been pre-dissolved in glycol ether, which makes them non-grain-raising (NGR). These NGR dyes are multi-solvent dyes that you can mix with water or alcohol. They’re more lightfast than powder dyes.
If you mix a concentrated dye with water, the dye stain will no longer be non-grain-raising, so you should pre-raise the grain by lightly misting the wood surface and gingerly sanding the surface once it’s dry. The benefit of using water is that you’ll have a longer open time than with alcohol, which helps you avoid lap marks when staining larger surfaces. Alcohol dyes dry much more quickly than water, so you can get back to work sooner, either applying a second coat of stain, or moving on to your topcoat. However, because they dry so quickly, they’re best used on small projects if you’re applying the stain by hand; for large surfaces, spray them on for more even coverage.
Dyes come in a few dozen colours. However, you can intermix dyes to create unlimited custom colours, making it easy to obtain the exact shade you want. The only caveat is not to mix a dye that was dissolved in water with one that was dissolved in alcohol or oil.
There are two prime sources for powder dyes. The Lee Valley brand comes in 1-ounce sizes in 26 different colours. TransFast dyes from Homestead Finishing come in 1, 4, and 8 ounce sizes in 42 colours.
There are also two popular sources of concentrated liquid dyes. The ColorFX line from Wood Essence is available in 0.5-, 2-, and 8-ounce sizes in 10 colours, while the TransTint line from Homestead Finishing comes in 2-, 8-, 16-, and 32-ounce sizes in 20 colours. Homestead offers a set of 2-3/4″ × 4-1/2″ birch plywood samples stained with TransTint dyes and top coated with clear gloss polyurethane. If you’re new to dyes you might want to consider purchasing the set – it’s an excellent resource to help you visualize a colour scheme for your projects.
Powder dyes and unmixed liquid dyes have an unlimited shelf life. However, once mixed they’ll be good for about 6 months.
Dyes are straightforward to apply and more forgiving than pigment stains. You can also tweak the colour more easily. As you would when using pigment stains, wear gloves and a respirator. And, because they can be somewhat messy to mix and apply, I also wear a shop apron and cover my workbench with a drop sheet.
Both powder and liquid dyes use the same dilution ratio of 1 ounce of dye (2 tablespoons) to 32 ounces of water or alcohol. Powder dyes require more preparation, which is why I prefer liquid dyes (all you need to do is dilute the concentrate with water or alcohol and you’re good to go.) Remember, the ratio doesn’t have to be exact – adding more or less dye will affect the intensity of the colour. Just record what you do, in case you like the colour and decide to mix a larger batch.
Manufacturers recommend that you should use distilled water if mixing a dye from powder, as there is a slim possibility that metal salts in tap water could leave spots on the wood surface. The powder will dissolve faster if you use hot, but not boiling, water. You’ll need to wait until the mixture cools before using it.
You can apply dye by brush, rag, foam brush, sponge or spray. For large flat surfaces I use a rag, while for small and narrow surfaces, irregular or turned surfaces, and hard-to-reach places, I use a china bristle brush.
What I find appealing about dye stains is that if you apply a coat and find that it looks too light, once it’s dry, simply apply a second coat to darken the stain. You don’t have to worry about obscuring the grain pattern of the wood. If you find the colour too dark, simply wipe the surface with water (or alcohol) to lighten the stain. You can, of course, increase or decrease the intensity of the dye colour by adjusting the dilution ratio. Less water or alcohol will result in a darker colour, and vice versa.
The colour on the surface of your project before the dye dries only gives an approximation of the final colour. If you want to know exactly what the final colour will be, apply the dye to scrap wood from your project (you may need to apply multiple coats to fine tune the colour intensity), and once it’s dry apply your topcoat. Record the dye-to-water or dye-to-alcohol ratio and the number of coats you applied on the back of the scrap piece for future reference.
If you plan to use pore filler on open-grained wood, apply the dye stain first, and after it’s dry, apply the pore filler. I use Aqua Coat, which is a crystal clear grain filler. Optionally, you can add dye to the filler.
You can add a liquid dye directly to a water-based or solvent-based finish, essentially making your own wood toner. Jeff Jewitt at Homestead Finishing advises that finishes thinned with a high amount of mineral spirits may not accept dye, and he recommends that you use gloss finishes rather than semi-gloss or flat. If adding to a water-based finish, stir in the dye for 30 seconds and then allow it to settle for half an hour before using. And, of course, unless you’ve previously used the dye with a finish, it’s advisable to pre-test on scrap wood to avoid being disappointed with the end results. Ensure that the final coat you apply is with the topcoat alone (no dye added). This will seal the surface and prevent the colour from rubbing off.
You can apply any topcoat over any of the dye stains mentioned in this article, though for a water-based dye be sure to seal the surface before applying a waterborne finish.
Getting started with dye stains requires a bit more experimentation than working with pigment stains, but if you’re looking for greater colour control, dying just might be the ticket.