Stain Mixing, Wood Tones, and Color Theory

      Starting with the basics, a cogent explanation of how to mix pigments and stains and how to use them to the desired effect on wood. May 18, 2010

Question
I've been asked to post formulas for these by others so here it goes. First off, pigmented stains are a combination of solvents and color pigments of different hues that have polymers - alkyds/acrylics or other binders such as drying oils present in the mix. This is done to help keep the pigment suspended better and longer, to keep the pigment from flocculating (turning into larger color masses) as well as giving ease of application and wiping properties on larger surfaces and other reasons. Unless you buy dry pigments and mill your own solvent pigment blend expect the colorants you buy to have some binder in them.

A pigment stain that was used extensively under shellac and nitro and acrylic solvent finishes since the 40's and even earlier was a simple mixture of mineral spirits and either universal colorants that were soluble in aliphatic hydrocarbons like naphtha/mineral spirits/ kerosene/ gasoline/ and most others, or Japan colors or colors in oil. Small amounts of linseed oil were added that gave more or extended working time to apply and wipe off on large surfaces. These were mostly hand applied with soft rags like baby diapers or loose knit cheese cloth among others.

To start to use these types of pigment stains you need to acquire a dozen or so of the colorants to have a good mix and match ability at your finger tips. We commonly had the ones listed always on hand with maybe a half a dozen or more in small quantities that were not used frequently. To start I would suggest you have:

Burnt umber
Burnt sienna
Raw umber
Raw sienna
Van Dyke brown
French yellow ochre
Yellow iron oxide
Lemon yellow
Bulletin red
Vermillion
Rose madder
Thalo blue
Thalo green (pthalo)
Titanium white - ti02 use to use zinc or lead - no more!
Lamp or drop black
Spinel black

These will be the backbone for largest part of your color needs. Others can be added as you have need, for sure a few blues/reds/and greens will come into play in time as well as yellows and different shades of the umbers. Make sure you buy these from a company that caters to wood finishing so you will get non bleeding colors, which should be no problem now. That's pretty much standard.

The solvent ratio formulas was such that no more than 20% colorant was ever added to the solvent or blended vehicle for use.

EX:
10% B. umber - 10 oz.
5% raw sienna - 5 oz.
5% raw umber - 5 oz.
To - 108 oz of mineral spirits = 1 gal stain.

This is not a color formula I use, itís just for demonstration. Normally youíre looking for about a standard of 10 oz per gallon which will fill many of your daily needs but making a stronger 20% standard starting out is ok also. To set up a color bench to use these or any others, start by mixing up pint or quart quantities of each color in a clear (preferably glass) container with lid. If you don't have them then milk jugs will do or other containers but be aware to change them every six months or so to avoid cracking of the plastic due to solvent action, to avoid leakage.

Metal cans can also be used, but of course you can't readily see the colorants. When starting out it's good to view the colorants to become familiar with the hues so that you recognize them second nature. It's actually your first step in learning some of the individual colorant's that you will be using for the rest of your career.

Since these will be your standards (and the amount of color you use in each formula should remain standard be it 10 oz or 20 oz) or anywhere in between, make sure you have good measuring equipment marked in increments of 1/4 oz. or less up to 4 or 8 oz minimum. For large batches you should have at least quart containers up to five gallons. This will come later after you actually start to use the stain daily/weekly. After you have mixed up your standards you will need to make up sample boards taped off that you can apply each individual pigment stain to so that you can become familiar with each separate color and the affect it gives on each type of wood used, this can be expanded as you have need or desire.

If you have made up your stains at the high level of 20 oz per gallon (20 oz plus 108 vehicle) start by thinning this out 100% and applying on the middle strip of the taped off sample board. Then proceed to thin out that stain 25% more at a time so you can see how this affects the color of the wood youíre applying it to (of course your free to do these increments in smaller reductions 5/10/20 percent), but this gives you a good overview for starters. Then do another board with the stain in increments of the same showing how the more concentrated stain also looks. Do not inter-mix your stains yet till you get a good feel for what strength gives you what over the wood's you've applied to. You may find that many times one colorant at a certain dilution level is all thatís needed to achieve what youíre after - only when this is not the case will it be necessary to start mixing up custom colors.

You'll find that when starting out the umbers will meet most of your needs either B. umber or R. umber or a mix of the two on woods like walnut or pecan, oak, ash or others, then this will lead you into adding very small amounts of reds/yellows/orange/green/or others to dial in a near perfect match. Your use of black to darken or shade the color is tricky - most blacks are strong and require but tiny amounts to darken or shade the color with. Normally this is added last just the contrary of tinting which usually starts out by adding color to white bases. The reds and some yellows can also be powerful so get used to adding very tiny amounts of these also when trying to adjust a color that you feel needs them to tweak the match your after.

Try as much as you can to try and achieve the desired color match with no more than three color hues. This may seem difficult at first but the more you do this the easier it will become. Most proís working in color labs do this almost without exception but then they have many other hues of colors to use many reds/blues/yellows/purples/etc besides what I have listed here. If you find you are having a difficult time matching a clients color, it will probably be because the original was made from pigment colors you are not using. Don't get frustrated, at the beginning you can always have it matched up professionally at your local coatings place or send it out for matching, till you become well enough versed to handle other colorant lines like huls/basf/ciba/ and others 844's or 896's etc. I find even now most wood stains can be matched with what I have posted - at least within reason.

Forum Responses
(Finishing Forum)
From contributor G:
Thanks for sharing your knowledge with us. These days the finishing forum and business forum are the ones I learn the most from. I find the forums on WOODWEB a great source of knowledge and inspiration! Finishing is one of those things that I am learning about and enjoy, except when things go badly. I try to stay away from the unproven and on the fly methods of finishing. Thanks to you and the others who post their experience and know how I am learning things that otherwise I would only find out after much trial and error and many mistakes that could be avoided.



From contributor F:
For a stain base, you are suggesting to simply use mineral spirits? Then to get the color, add some artist colors or Japan colors? Do I have the basics there?

Now to go to the next level. Use a clear stain base and some HULS colorants. How do we make this stain base or do we just buy it from ML Campbell or whomever? Now on to the next dilemma Ė blotching. When I stain a wood like cherry, I will typically use a clear stain base "ML Campbells for example) as it claims to have 10 or 20% solids (canít remember the exact number), let that dry, then go over it with a wiping stain. This really helps to control the blotching. How do we now control blotching using our homemade stains? Use the same clear stain base? Use a washcoat with lacquer or shellac?



From the original questioner:
The mineral spirits is your vehicle chosen for open time in application of the pigmented stain. You may choose to use another aliphatic like VMP naptha for faster drying, or a slower type like 150 high flash, any number of solvents with differing evaporation's can be used or combined. The MS was or is used because it's a good intermediate evaporator but youíre not stuck with just that. No, it's not just color and MS - the colors provide your binder (linseed oil - raw or boiled), which keeps the mix together and from settling out so easily. That's what usually is defined as a stain base - solvent/binder/color. You can use it without the binder although you have to agitate it a lot to keep everything uniformly suspended - something we did quite frequently in the field. Artist oil colors are ground in raw linseed normally. I'm talking of industrial colors in oil in quarts or gallons available from coatings mfg.'s or other color sources. Some of them also make colors with raw oil but the difference is there is the grind of colorant (particle size) is usually bigger than in fine ground art colors and much cheaper seeing as the purity is lower. Delta labs would be an example of such who have these types of colorants. Japan colors on the other hand are an alkyd base colorant that have good weathering properties and are used more by sign painters than finishers because of their weathering ability. But they are also good to use for wood stains if so desired. Since they also have a drier in them cobalt to dry the alkyd, they tend to set up in an open container unless you use a bloxygen or other inert gas to evacuate the oxygen from the can before sealing the lids. Or use marbles/ball bearing/ or other to bring the level of colorant back to the top of the can which is a pain. I only use them when I ran out of the colors in oil and was in need of getting something quicker than could be had by ordering them because a store right up from my shop carried them. They also settled harder once they laid on the bottom of the can/jar/etc. than the oils do. I'm not against them I just feel the oils are easier to work with. It's funny, when I got into the business no one cared about what is described as blotching. To us that was just the properties of the wood and also delightful to see - it gave the wood character that plain woods did not have.

I would rather see finishers start to sell the natural qualities of the woods they use (like some now are doing) instead of continuing to try to please the designers and architects who started this trend of color uniformity in opaque color schemes and have ever since tried to press it upon stained wood surfaces.

If you want to diminish this affect you can do these things without using a store product, most of which your already familiar with. You have already mentioned shellac and lacquer - nitro or acrylic sanding sealer's can be use also, so can thinned out coats of hide glue sizing (liquid hide glue thinned out that will also let your dyes penetrate it with better uniformity). Or you can continue to use the alkyd type your now using that also have other additives in them to do this.

Adding bentonite a type of clay to a mixture of BLO and MS will work also, so will using a slower evaporating solvent application before applying your MS based stain, when the wood is whetted with high flash naptha 150-200 - it stops the over stain from being able to penetrate the wood as much, but - it may also lighten the stain color you have mixed so keep that in mind so you can do samples and see if the stain needs to be strengthened or not. But for you i would stick with thinned out coats of sealer and experiment with the others as you have time.

Start by diluting a full strength sealer at a ratio of 5% sealer to 95% thinner and bulk up from there as desired - be careful though a common mistake when making samples with the use of this method is to test it out on pieces that have not had adequate time to dry and then when put into production act differently than they did on the samples.

Meaning, if you for example have a job that has let's say 4x8 panels in a mix of smaller panels or doors drawers etc., and you seal all of these in with the thinned coat of sealer you used to make samples for the project on, keep in mind how long it was (write it down) before you applied the stain over the sample. If you don't - what you will find is that though it worked well on the sample that you let set for an hour or two before staining, it' s not working on pieces that have set all day or overnight or longer, the reason being by then all of the solvents have evaporated out where as the sample was still bulked up with presence of still incorporated solvent(s).

Once the lacquer has released all of the solvents it contains give or take a percent of slow driers that may be there at 1 or 2 percent. The film has reached its point of thickness in which it will remain throughout the span of the finishing operation it's being used for. So if you end up with a 90/10 seal coat or 85/15-80/20 or whatever works the best on each individual job, make sure you wait over night at least before making a determination on whether it's working the way you want or not, otherwise you will be disappointed in results when applied to the job itself. Also donít cheat! Do not try just saving time by applying two coats of thinned sealer at the same dilution ratio! You will only end up resolving the first coat and having to wait even longer to get accurate results.



From the original questioner:
I left an important note out of using the clear for a blotch conditioner. You have to sand the bulk back off so the stain can penetrate the wood just like you would with using a thin coat of shellac or any other clear resin sealer. All youíre trying to do with any so called conditioner /sealer is to stop the penetration of the stain, into the wild or soft portions of the wood not totally block the stain from being on the wood surface. Too thick of a coat applied without sanding will just act as a glaze not a conditioner. If sanded back off the non problem areas, then contact with the normal wood surface will behave as usual.



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