Artist's Oil Paint As Color On Boxwood

[Janel]

Several years ago I enjoyed using artist's oil paints to color my pieces that were carved in boxwood. I will add a few thumbnails from my web site as examples:

 

 

 

 

 

One piece that was borrowed for an exhibition in a museum/gallery exhibition (not a full scale, controlled lighting museum) sustained enough light exposure to fade the faint green oil color that was applied sparely to allow the wood to show through. The wood darkened enough that the difference between the green, and elsewhere some lighter and darker brown thinly applied as contrast to the lighter boxwood when new, changed to be of similar tones to the paint. The changes horrified me and the clients were very disappointed. The piece was a very expensive purchase for them.

 

I used artist oil paint on boxwood. Later I will note the kinds of paint used, after I go to the studio.

 

At some point in time more recently, another artist mentioned using something to seal the surface to prevent absorption of the oil. Another point mentioned was that there are differences in what the colors are made of, mineral vs something else that could change that is not a mineral (I think that is what I recall, it was long ago).

 

 

Thank you Mark for offering to help me understand more about what I could/should know if I hope to return to using oils for color.

 

Janel

[Mark Strom]

Sorry to hear what happened to your work and I understand your pain there. It is because of incidents exactly like this that I have spent months researching this process. Below is what I have learned so far by talking to manufacturers, looking at MSDS sheets, learning about thinners, binders and pigments and consulting with several classically trained restoration artists.

 

The main reason Janel had this problem is not due to the paint fading but due to the color change in the wood, absorption of oils and most likely improper thinning of the paint. Most semiprofessional or professional grade artist oil paints will have very little fading in color straight from the tube. The difference in the quality of the paints is the amount of inert fillers, amount of pigments and the quality of the binders. The light fastness and opacity is usually printed on the side of the tube. Without naming products let's say there are three tubes of paint all the same color. The binder that holds the pigments together to form the paint is usually linseed oil which can vary greatly in quality. The amount of pigment is the real difference. The cheapest tube will have the least amount of pigment, lowest grade of oil and the most amount of inert ingredients to "stretch" how much paint can be made from x amount of pigment. Basically paint is just like gasoline...higher grades are more refined and perform better. Top quality artist oils use the best oil, the most and purest pigment and the least amount of additives.

 

When painting or glazing you usually thin the paint with a thinner. This increases the flow and reduces the drying time. Pure linseed oil takes a long time to dry. Oil paintings are usually varnished to seal the paint and avoid the collection of dust...the standard is to wait 6 months to a year to allow the layers of paint to dry sufficiently so that it does not react to the varnish. Each different thinner affects the drying time or open time either faster or slower. You can thin the paint to thin with the wrong thinner and actually destroy the paint by removing enough binder where the pigments will break down and nothing holds them together. So matching the thinner to the paint and purpose is important. Glazes are usually thinned paints in a medium that increases the open time so the paint can be manipulated for different effects. The glaze is usually a combination of a binder, thinner and in the case of oils a varnish. There are glazes such as Liquin that are chemical in nature and dry due to chemical reactions instead of drying through evaporation. There are other variables that can speed up or slow down the drying times for paints and glazes by adding different thinners and dryers.

 

One thing to always take into account when leaving natural wood is the aging process of the wood, knowing what the end color will be. Walnut turns yellow, cherry turns brown, maple a honey color, so this needs to be anticipated. I usually seal the wood with thinned shellac to get closer to the aged wood with basswood. Sealing with shellac also keeps the wood from absorbing the linseed oil which will also tint the wood. The color of the finish needs to be taken into account as well. Some varnishes yellow, some glazes do the same while there are some finishes that are not as bad to change.

 

Sounds like a lot to learn but there are just a few binders and thinners to work with when it comes to oils, the trick is you just have to find out what to use to get the result you want.

 

Mark

www.stromcarver.com

[Yuri]

Janel, I'd try to find a really knowledgeable dealer of artists' supplies. The kind that also stocks restorers' materials. I know I have one not far from me, and he'd know all the answers to these questions. Restorers come up against this sort of thing all the time.

[Janel]

Mark,

 

Thank you for the in depth response. It does sound like a lot to learn. You are very right about the wood changing color, and the influence of the oil in the paints. Yes, I did thin the colors when applying them, and applied the pale green sparingly, allowing the wood to show through. That green color was described as a semi-transparent paint, with good color fastness. I glanced at the label but did not write anything down tonight. The main problem was the oil/wood/age/light relationship, which overwhelmed the very thin application of color.

 

 

 

Generations 1999

 

I would like to ask you some questions about using the thinned shellac. Once applied, does it make the surface hard or carved parts sharp or edgy? Would it leave the wood feeling like wood or like it was coated with something?

 

One of the things that I like about oil paints on wood, is the feel of it after it is long dried and has been buffed gently and thoroughly with a brush or cloth, which ever is right for the piece. I have tried using acrylic paint on one piece, which made it feel like plastic.

 

Another question about shellac, does it dry quickly, as in would I have time to remove excess from the minute recesses that my carvings tend to have? I would not want to loose detail before being able to accent it with the color.

Do you have recommendations for how to apply it to work such as mine? Would you suggest a recipe for thinned shellac? I purchased the dry material quite a long time ago and never mixed it for use.

 

Here is a question that is different but related. We have discussed bleaching wood in past years here on the forum. Would a piece of boxwood bleach to a more pale color, and then remain pale into the future and when shellacked and/or colored?

 

Thank you Yuri. I will need to do some homework to figure out where to go for well recommended supplies and information. There is a restoration company that works independently of, but is located in the building of, the Minneapolis Institute of Arts. It is quite an impressive place (I did go there once). I do not know of individual restorers, but I never tried to find one of them before.

 

Thank you both,

 

Janel

[Mark Strom]

I remember seeing that piece. This is the very reason that I am going back to the old school way of working. By that I mean learning how the finishes work, what they are compatible with, what to anticipate and what all the finishes are composed of.

 

Linseed oil is the base for almost all artist oil paints, the exception being the alkyd oil paints. This oil slows the drying time, creates the strong film that seals and holds the pigments, gives a long open time to work with the paint but also is what creates the problems such as, yellowing, improper drying, cracking and finish incompatibility. Understanding how things work is part of this but also knowing why it works is important too.

 

I paint some of my carvings with watercolors first to get my base colors and to speed up the finishing time. The downside to this is the risk of using to much water and raising the grain. When this does happen I use a 3M white micro pad to polish the fuzz away. I then seal the carving with a 1 lb. cut dewaxed white shellac which is a very thin shellac, almost 50/50 shellac and denatured alcohol. This seals or gives the carving a washcoat and seals the watercolor in. It dries very fast and should be brushed on with a good quality brush, put on a even coat in one pass and do not mess with it as it can dry really fast and capture brush strokes. The shellac this thin can be applied in two coats with basswood and the wood still looks almost unfinished. It brings out the grain but does not build a film or shine, on harder woods like boxwood 1 coat would probably be enough. The idea is to apply enough to where there is just a hint of shine or surface film. The shellac still gives tooth for stain or paint, does not obscure or build in corners or alter your ability to apply other finishes. It can be sanded, buffed or scraped at this point without any problem as the shellac has been so thinly applied. If it does build in unwanted places it can be soften with denatured alcohol and cleaned up, shellac is also a reversible finish. Shellac will cover any paint and any paint can be applied over it...even watercolors if applied straight from the tube. This shellac washcoat will also prevent linseed from penetrating or spreading into the wood causing discoloration.

 

Oil paints come in different types but what I use is either the artist oil paint or the artist oil alkyd paint. The first is linseed based and colors can take from 2 to 12 days to touch dry and are reversible. The alkyd oil paint is a modified resin paint that drys in most cases within 24 hours and cannot be reversed back to the original state. Glazing medium for the oil paint is usually a mixture of linseed, turpentine and varnish which can thin the paint to any degree of translucence. The downside is this glazes yellows is slow to dry if you are in a hurry and only has one sheen which is a eggshell look. You can manipulate it longer and use some techniques that are difficult with the next method but it too is reversible. The glazing medium for the alkyd paint also contains the alkyd resins with additional thinners but they start to stiffen within a couple hours and dry to a hard film within 24 hours, they come in several sheens and are also available in gels or thicker mixes. They also do not yellow anything like the other glazing medium. Like the alkyd paint they are not reversible . So for real speed use the alkyd paint and glaze.

 

Now for a twist. You can add a little of the alkyd glazing medium to regular oil paints to speed drying time but only if the paints underneath were put on using the same method. If a fast drying paint is put over a slow drying paint then cracking or flaking is the result. There are pros and cons to each paint and glaze and each has subtle differences in appearance, especially over time.

 

As for anticipating the wood color change so that a proper and subtle glaze can be applied, that can be a challenge depending on the wood. Bleaching can be done very easily with a 2 part bleach which removes the color from wood like bleach on clothes. Boxwood is hard and dense so it will not bleach as fast and depending on the color may need multiple coats. It does raise the grain to a degree depending how fine the sanding was beforehand. It also has to be neutralized with a 50/50 white vinegar mix which also may raise the grain. The bleaching does not penetrate very deeply but even so it takes a fair amount of sanding on the surface to get back to the true wood color. I have even used light sanding to add tones to the bleached finish. This color change is permanent, the wood will never go back to the original shades it would if not bleached. Almost any clear finish applied will yellow to some degree, varnishes more so, shellacs less and nitrocellulose lacquer the least.

 

More information to digest. Oil painting is really and exercise in chemistry.

 

Mark

[Janel]

Thank you Mark, for the tutoring. It is more than I knew about this subject. I applaud your commitment to learning about the coloring mediums that you are using, and appreciate your willingness to share your knowledge.

 

I will explore using a shellac mixture on test wood as a start.

 

Here is 'horrors' question: is there a spray shellac version that might apply a light coating, or be applied lightly more than once to ensure full sealing? It might not be advisable but I wanted to ask anyway. I cannot guess at how well I could neatly control the application of liquid on a complex carving.

 

Hmm, you are right, an exercise in chemistry. What a thought!

 

Janel

[Mark Strom]

Sorry it sounds so complex, in a way it is complicated but then again once you understand some basics things start to make sense. I use the Zinser shellac from Lowes or the Depot which comes as a roughly 2 lb cut. Shelf life is maybe a year. It is beyond use when it turns dark or will not dry. There are plenty of formulas on the net for shellac mixes. I take measuring spoons or cups and mix it 1:1 with denatured alcohol. This not a precise 1 lb. cut but is good enough for me. It is very thin, dries really fast (20 to 30 min.) and absorbs enough where I do not have to worry about being precise about my application. You should be able to do this with your work easily, of course experimentation is always best before applying something unknown to work that took more than 5 hours to complete. It is hard to make a mess of it unless applied very thick in a heavy build and if there is a problem just use straight denatured alcohol to remove it.

Sprays are difficult to get in tight spaces, difficult to control and they do not penetrate as well.

 

One other thing of note. It helps to know how a finish dries. Shellac,lacquer and varnishes dry through evaporation leaving the resins to form a film. Oil paints dry through oxidation where the finish interacts with the oxygen molecules to form a film, contrary to conventional thought heat does not speed up this process as with the evaporation. Alkyd oil paints dry through polymerization which is a chemical reaction so when the drying starts to kick in a chemical reaction takes place and its done, epoxy is a good example. Acrylics dry through a method called coalescence.

 

Mark

[Janel]

Hi Mark,

 

"once you understand some basics things start to make sense"

 

I know what you mean. I do know about some of what you have described, but from so long ago and with little practice or repetition, it remains as disconnected bits and pieces.

 

Your succinct description of the differences in how the materials dry is very welcomed and is also interesting to learn about.

 

Might there be a text book out there somewhere that has this put together for reference? You have done a good deal of research to be able to pull this knowledge all together, and to be able to share it. I appreciate your desire to know things.

 

Janel

[Brian I]

I would just like to add:

 

Possibly do several layers of thinned paint? This would help build up the opacity to some degree and may help the colour to stay strong.

[Janel]

Mark, I have a couple of questions.

 

The shellac sealer that I have is four years old, and is a golden, perhaps darker golden color. Is it too old?

 

I made a 1:1 mixture and applied it by brush to a test piece of boxwood that was carved with similar textures and undercuts. Since the piece is strong with end grain on front and back, the test piece is also oriented that way.

 

When applied, the mixture soaked into the endgrain very quickly, the wood is very thirsty. After about 20 minutes, a drop of moisture on the end grain was absorbed a bit, and to me that means that the grain is still open and thirsty. I think that another application is in order, since I don't want the oil paint to be absorbed. What do you think? And, should I use the shellac from the can instead of the dilution?

 

Thanks,

 

Janel

[Steve Duryea]

Flake lac has an indefinite shelf life if kept in a reasonably airtight container, Janel. It doesn't matter if you use blonde or even orange flake instead of bleached. The color of the shellac will have no influence in such thin coats. I would avoid canned shellac. It's best to make your own solution. It'll take more than one coat to completely seal endgrain. You could use a heavier cut, but since it dries so quickly, just as easy to use a thin cut with multiple coats.

 

Linseed oil yellows more than walnut, safflower or poppy, but makes for a tougher film. This may be a consideration if your pieces get handled a lot, as netsuke often are. Most manufacturers use safflower for whites. Overthinning, as Mark has said, can create difficulties. You don't want underbound paint. The most appropriate thinner is artist grade turpentine or oil of spike. OMS, far as I'm concerned, is for cleaning brushes, not thinning paint.

 

There are very few single pigment greens-- viridian, opaque oxide of chromium, phthalocyanine, cobalt, that's about it. All have the highest ASTM rating for lightfastness. Blue and yellow mixed greens may present problems, since some yellow pigments are less lighfast than others.

 

Mediums are a whole other ballgame. Unless you really get into researching them, best to do without. Many oil painters prefer to use the paint alone, no mediums. I don't recommend using Liquin unless you're using alkyd paints. I know it's popular but I also know people who have had trouble with it down the road. Nor do I recommend using a varnish top coat unless you want a higher gloss and more yellowing.

 

There are two ways to think about accelerating drying rate. The first is that if you want a fast drying paint, don't use oils. The second is to use a drier. The best drier for oils is liquid lead napthanate, which dries the film from the inside out, unlike manganese or cobalt driers. It's perfectly safe to use if you take simple precautions.

 

Far as brands, I suggest Old Holland or Robert Doak. OH are linseed based, Doak are walnut-safflower based. OH is very expensive but is the almost universal choice with bird carvers, except for the few who know about Doak and go with him for ultrapricey pigments like the cobalts. Doak is considerably less expensive but the quality is just as good, though his paints have a much longer open time and are best used with lead (he stocks it, or used to anyway) unless you don't mind waiting a long time for them to dry. Williamsburg also has a good reputation but I haven't used them, ditto Natural Pigments. Blue Ridge is run by Eric Silver, who I believe studied with Doak, and he has many of the same colors, but he uses a mix of linseed and walnut oil instead of walnut and safflower so the paint probably dries faster, haven't tried it myself.

 

It's possible to use acrylic without getting that plastic look, but for arcylics, Golden is it. Forget every other brand. Get in touch with them, these are extemely knowledgable and helpful people. They make a huge line of products, all of the highest possible quality.

[Janel]

Thank you! I look forward to finding and trying some of your recommendations.

 

Janel