Adding Dyes to Tung Oil
Detailed advice on mixing and applying your own custom-tinted Tung oil toner. (Also, dispose of the rags with care.) July 3, 2008
Question
I have read here about Twisp environmental and Lockwood dyes. I am about to start making some finish samples of sassafras (for furniture). The products I am going to try are the 75/25 tung oil and silver grey oak powder dye. I was wondering if you could give me some advice on making a toner. I want to top coat and get color in one step. I do not want it really dark, so that is why I thought I could do it in one step. Any recommendations on number of coats?
Forum Responses
(Finishing Forum)
From contributor C:
Is the dye an oil stain type (solvent soluble?) Does the sassafras have a light yellow appearance? Chairs/tables/other? Is this for your use or a client's? Have you used tung and oil dyes before?
From the original questioner:
I have not used these products before and the dye is oil based. The sass does not have a lot of yellow in it. Bedroom furniture, client.
From contributor C:
Dissolve the dye in turpentine, stir until dissolved, strain the filler out of the dissolved dye (that part of the dye that does not dissolve). Use multi folded cheese cloth for this operation. Make up a thin formula of the dye and tung oil - dilute the 75% tung by two thirds to 25%, add the dye to the diluted tung, and apply this to the sassafras.
Make sure you do samples first. If the color is too dark, you can add mineral spirits to dilute it further; if not strong enough, you can add more dye. You'll have to get back to me on how dark you plan on going. Otherwise, you can also add some dye to the 75% tung after you're through applying the thin dye/tung coats. Dye tung coats should dry for at least 8 hours before applying the next dye/tung coat. Your final coats should not contain any dyes. It is good practice to burnish the tung with a scotchbrite or steel wool pad to work it into the wood. I use a small d/a with a nylon pad adapted for this purpose. There is little waste of the tung and less oily rags to deal with if done this way - no residue to remove.
In the future you may want to use a water soluble dye instead of the oil base - better light fastness. But the oil dyes have acceptable fade resistance. Especially if they're built up in stages as you're doing. Since the color you selected is shown on oak - it will look different on sassafras, which has a wide range of color - if you know basic color theory you should in the future buy the concentrates in primaries - red, blue, yellow and black to tone so you can make colors that suit different types of woods.
From the original questioner:
How much dye do you add to the 75 tung? I know this will vary. Do you strain this as well?
From contributor C:
You can add as little or as much as you desire, but this should not be done on the last coats - you want just tung for the final coats. All dye will have to be strained if it's in powder form. They add fillers to balance out the dye amounts that do not dissolve. Liquid dyes do not have to be strained if purchased in that form.
From contributor C:
You have to be careful with the thin mixtures you first put on - they may lift to a degree if not allowed to harden thoroughly. As I stated, at least 8 hours drying, and if it's cold or high humidity, much longer. I usually put it on in the daytime and come back the next day to apply the other clear coats over it. And remember, this is just a toner coat - some of the color will be to the surface of the oil till it is well built up, keep that in mind. As I said earlier, it's better to use a direct dye on the wood even if you have to seriously thin it out to keep it light. It penetrates better with a water dye and you don't have to worry about bleed or resolving of the dye/tung coat. But if you're determined to go the route you're on, be my guest.
From contributor W:
I am sure you know, but please make sure you soak those rags in water if you wipe any of that stain you made with turpentine and tung oil. It is really prone to spontaneous combustion.
From contributor C:
Good point - you can also stop the heat reaction by hanging the rags up individually. Just don't make a pile of rags - the hydroperoxides that form during curing are what make them become hot and prone to autoignition. As long as air can circulate over the rags combustibility is not possible, as there is no way for the heat to build up. I have seen this happen only when many saturated rags were piled together after being soaked with oil, tung or linseed, and left in that state for many hours.
From contributor R:
As safe as you would think it would be to just hang up a rag and let it air out, it's basically a fine waiting to happen. Both OSHA and the fire department frown on such a practice, mostly because they want you to spend money on one of those fire proof cans with a self closing lid. Let's all stay safe out there.
From contributor C:
42 years and counting hanging rags - no fires, no smoke, no heat, no problems. I surely agree with self-closing lid metal containers. I did see a fire where, even though the 3' pile of rags was put into a water filled drum and the metal lid put on, the top portion of the rags did not get covered with water. That night a fire broke out - 1982 in Grand Rapids, MI. I've never had singly lined up rags do anything but dry out in a few days hard and then they can be thrown away in the trash - once the oxidation has totally transpired and all the oil is hardened, solvents evaporated, etc, there is no problem.
From contributor R:
No-one mentioned fire, my posting said "fine." I know all too well about that fire - anyone who overfills a drum with oily rags and then tries to put an ill-fitting top on is only asking for trouble... or fire. Even with your years of doing what you've been doing, it is now illegal to "just hang up a rag." Just like spray-booth filters, it's against the law to dump oily rags into a dumpster, even if they are dry. All of this is now looked at as hazardous waste and must be disposed in a proper manner.
These environmental laws may not seem to be a big deal, but are just some of the restrictions that we now have to contend with. I've hung up rags for year upon year and have never had a problem, but the industry has changed and OSHA regulations have changed and the Air Quality District laws have changed. Just log onto your States regulations to see just how things have changed. As silly as some of these laws are, they are the laws a finisher is obligated to follow, especially if they are prone to posting their opinion on the world wide web.
From contributor C:
Dried polymerized oil is not a toxic chemical, nor a hazardous waste - if it was, you could throw no natural coatings away, including sour milk, walnut oil, or other drying or semi drying oils. Only if you're using tung with driers is there any hazard of pollution or requirements.
From contributor R:
You mean like the ones you were talking about in your answers above. Those were the ones I was talking about.
From contributor C:
Any rags that have metallic dryers would fall under EPA and other. If oil you're using is not 100% pure tung, no dryers, no EPA banned or listed solvents, or any other listed substances, let them dry and dispose. If they do have - handle them in the manner which prevails in your vicinity, state, or by federal legislation, law, or other. This should be common knowledge to all in this business.
