Oil Finishes: Reducing Color
Change on Light Woods
Overview: If you've ever finished a light colored timber like Ash with traditional oil finishes, you have no doubt been surprised by how much the finish can darken the color of the wood. While this color transformation may be the desired effect you are looking for, it may not be pleasing at all. Many of the finishes that are available can be quite dark in the can. When a dark oil finish is applied to a light colored timber like White Ash, Holly, Sweetgum or Maple, the color of the wood may be significantly darkened, or worse yellowed.
Luckily, there is an easy way to prevent this problem. The solution will keep your timber truer to its original color and save you money at the same time by reducing the amount of oil finish required to achieve proper build. To prevent your oil finish from darkening light colored woods; simply seal your project first with a lacquer or shellac sealer, prior to finishing with your oil. Let's take a look at this in more detail.
Sealing the Bare Wood Surface with Lacquer
I have been sealing my light and medium colored timbers for many years prior to finishing with solvent based oil finishes. I typically use Deft clear lacquer and make up my own sealer. In the can Deft is too thick, so it needs to be thinned with lacquer thinner to achieve proper application viscosity. Mix equal portions of Deft lacquer and lacquer thinner (50/50 mix) and stir well.
This will make a thin lacquer sealer that will penetrate the wood easily. I typically flood this onto the surface with a brush until the wood will not accept any more sealer. Wipe off any excess with clean paper towels and let dry thoroughly overnight, or for a couple of days depending on the weather. Once the sealer has dried, cut it back with synthetic wire wool, or fine grit sandpaper like 600-grit or higher (use the highest grit you sanded your project to). Remove any surface dust with a tack rag, or some compressed air before proceeding.
You can now apply your favorite oil finish in multiple light coats to the piece without worrying that there will be a significant color change. In addition, since the wood fibers are now sealed, you will find that you will use less finish to produce the proper build. This can save you a significant amount of money if you are using an expensive oil finish. Some of the oils in my studio cost upwards of $40.00 per quart and by sealing the bare wood before applying the oil, I can typically save about 50 - 75% on finishing costs.
Remember to lightly cut back the surface of the oil between coats and remove any dust before applying the next coat of oil. The number of coats of oil that are required depends on the product and your personal preferences. Most of the oils in my studio require between three and twenty-five coats to achieve the proper build.
Sealing the Bare Wood Surface with Shellac
If you prefer Shellac, look for the Super Blonde, or Platina varieties, which are the lightest grades you can buy. I prefer to use raw dewaxed Shellac flakes and make my own Shellac up as needed. The reason for this is that Shellac has very short shelf life once it is mixed with the solvent. By making it up in small batches, you are assured of fresh product.
Denatured Alcohol is used for dissolving the shellac flakes. I prefer a 1lb. cut (2 oz. of flakes in 16 oz. of alcohol) when making a penetrating sealer. Pour the alcohol into a glass container and add your Shellac flakes. Stir the shellac a few times over the next couple of days. When all of the flakes have melted, stir the shellac well and strain it through a fine mesh paint filter, or cheesecloth to remove any impurities.
If you do not purchase dewaxed shellac flakes, be sure to dewax your shellac before using it. Once the shellac has been strained, let it sit for a couple of days to settle out. You will see a cloudy layer form in the bottom of the glass, which is the wax. Simply decant the Shellac that's above the wax to remove it. The remaining Shellac is good for at least three months if kept in a container with a tight fitting lid.
The thin Shellac sealer is applied the same way as the lacquer sealer, flood on and wipe off any excess. Allow the sealed item to thoroughly dry for a couple of days and then cut back with wire wool or fine abrasives. Apply the desired oil finish in multiple light coats until the proper build is achieved. Always let the piece dry overnight between coats of oil and lightly cut back the surface with wire wool, or fine abrasives before applying the next coat of finish. If you would like further information about using oil finishes, check out my
Oil Finish Roundup
article in the main library.
Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.
|Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments. |
Steve is also a regular featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his monthly articles covering technical topics, or project based articles in each issue.
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