Double dye stabilizing is a great way to add a little pizzazz to your turning blanks. It imparts color throughout the entire piece of wood rather than just the top layer, plus it stabilizes the wood at the same time eliminating wood movement and adding structural integrity to wood that is brittle, cracked, or soft. When the double dye process is applied to a highly figured piece of wood or a burl, the results are simply amazing!
Step 1: Equipment and Supplies
Dye stabilizing is not a terribly difficult process once you have the equipment needed for vacuum stabilizing. The materials and equipment required include a vacuum pump, vacuum chamber, Stabilizing Resin, Dye, an Oven, and of course some wood. You'll also want to get some rubber gloves, cups, and something to stir with like wood craft sticks. Once you have the equipment and supplies, you're ready to get started!
There are a few choices on the market for stabilizing resin, but I've always used Cactus Juice brand with great results. I also use Alumilite brand dyes, which is completely compatible with Cactus Juice and also has the advantage of crosslinking with the resin when cured.
I use a Turn Tex vacuum chamber, which is a great product for wood stabilizing due to the increased visibility being a clear pipe. There are many vacuum chambers on the market that work well, and you can even build your own.
There are a wide range of vacuum pumps on the market as well, and I have decided to go with an import model that is fairly cheap with a good reputation. The Robinair 15310 is a single stage 3 cfm pump that works great, and if you want a little more power a two-stage pump will pull provide a slightly deeper vacuum and will get to full vacuum faster. However, a single stage pump will do the job just fine.
The best oven to use for drying the wood and curing the resin is a cheap oven. It is important to also use an oven thermometer to ensure the temperature is correct. Almost all oven temperature gauges are inaccurate.
Step 2: Preparing Your Blanks
The first step to get the wood prepared for stabilizing is to completely dry it out. I bake the moisture out of the wood using an oven. How long it takes depends on how much moisture content it starts out at, the size of the wood, and the species. For smaller pieces that have been cut and have relatively low moisture content to start out, baking the pieces overnight in an oven set around 225 degrees F will usually be enough. The best way to know when you are done is by weighing the pieces before baking, then checking the weight periodically. When it stops dropping weight, the wood is at or near the 0% moisture content that is needed.
I typically cut the wood into blanks slightly larger than the final dimensions will be. By cutting it down, they will dry out faster. It's best to keep them a bit larger at first and cut them to final dimensions as the final step in the process.
Step 3: First Dye Stage - Highlight Color
The first dye stage is what I consider the "highlight" stage. No vacuum is needed for this step, just fill up cups with dyed stabilizing resin and let it soak up the juice and dye. The wood will pull the dyed stabilizing resin into the wood fibers through capillary action. The amount of saturation is dependent upon the wood species and how long you let the piece soak.
This first stage can be really fun. Although the title is "Double" Dye stabilizing, multiple colors can be added to each piece of wood. Keep in mind, the colors will bleed together; however, areas where colors blend together can provide even more interest to the look of the blank. Once the wood has soaked up enough color, the wood is baked in the oven to cure the stabilizing resin and lock in the colors.
Step 4: Remove Excess Resin After Baking
After the highlight color has been baked in, any excess resin on the outside of the blanks should be removed. If the excess resin is left on the outside, it will inhibit the resin from penetrating the blank on the second dye stage. This can be done by scraping it off, sanding it off, or cutting it off. I typically use a disc and belt sander to remove the majority of the excess from the sides and ends, and scrape off any excess in cracks or on odd shaped parts of the blank.
Step 5: Second Dye Stage: Full Vacuum
Once the excess resin has been cleaned off the blank, it's time for the second dye stage. In the second stage, the blanks will submerged completely in resin and placed under vacuum and fully stabilized. The process requires a vacuum chamber and a vacuum pump. During this process, the air will be evacuated from the internal structure of the wood, and dyed resin will be forced throughout the wood once atmosphere is reintroduced into the vacuum chamber.
Because the blanks already have cured stabilizing resin inside, it may take longer to remove all the air than if the blanks did not have any cured resin in them. The blanks will need to remain under vacuum until no more air bubbles surface in the chamber. Also, it is important to cover the blanks with resin in the chamber. It's best to cover them by at least 2-4 inches because the blanks will soak up a good deal of resin once the air has been removed.
Once all the air has been removed, the vacuum pump can be shut off and the blanks need to soak in the dyed resin. I generally soak the blanks overnight to ensure the resin penetrates the wood fully. Then, the blanks need to be baked to cure the resin and lock the second dye stage colors in the wood.
Once this step is completed, the blanks are ready to be turned or cast in resin. You could also continue adding more colors under vacuum, but once the blanks have been fully stabilized each additional step will take significantly longer under vacuum and soaking.