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Old 11-29-2008, 04:30 PM   #1
Richard Bingham Richard Bingham is offline
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Thoughts on painting mediums




Quote:
Originally Posted by Jennifer Bogartz
. . . I am currently using walnut oil, walnut/alkyd oil, and liquin . . . (not all at once) . . . I have heard some negative things about alkyds . . . such as delamination . . . Does an artist need to try many different mediums and varnishes in order to become well acquainted with them?
A good number of painters whose work I greatly admire are proponents of painting entirely without the use of any mediums of any type other than the occasional sparing use of "cold pressed" linseed oil. They claim that any and all effects which may be achieved in oil painting can be accomplished without the addition of resins or treated oils of any kind, and the quality of their work attests to the validity of their claim. In addition, they point to the wide pharmacopaeia of painting mediums as the source of all paint failures such as cracking, poor adhesion, wrinkling, darkening and yellowing. Again, their position is unassailable in consideration of a permanence that may possibly extend 500 years and more.

That said, (and I realize this statement is open to contention) considerable physical and experiential evidence supports claims from the other side of the fence that "Ye Olde Masters" did, indeed, employ various oils and resins in preparations and in combinations as "painting mediums".

This brings us to the question of what is a medium, and why should one use it? Considering the merits of the "No Mediums" position, the only good reason for employing a medium is to enable the painter to achieve effects or results which would be inefficient or unattainable without them.

What a medium is NOT:
It is not a diluent (thinner)
It is not a siccative (drier)
It is not (whatever its composition) applicable in every painting situation at all times
It is not a "final varnish" or a substitute for retouch varnish or "oiling out".
It is not a belief system, a talisman or a religion that will give the user the powers of a Raphael or a Velasquez.

What a medium IS:
It is a "paint additive" that makes paint from the tube handle "different" than it does without it.
Mediums DO allow paint strokes to stand up, or "stack", enable painting wet-in-wet, sfumato effects in overpainting and overglazing, enable paint strokes to flow out and settle without textural marks, and enhance the brilliance and clarity of some pigments, etc.
A resin medium is normally a balance of three ingredients: 1. resin selected for the specific properties it imparts to paint
2. a solvent which brings the resin into solution and controls the viscosity of the medium in handling and drying
3. a drying oil (preferably linseed) to impart flexibility in the resulting paint film, as most resins are brittle
Oil mediums comprise a number of different drying oils (e.g. linseed, tung, walnut, poppyseed, etc.) which have been heat treated, partially polymerized, cooked with metal salts, sun-bleached, sun thickened, etc. etc. and having properties different from the raw oil in which the colors are ground are thus capable of altering the "handleability" of tube paint.
As well, the wide variety of possible mediums certainly includes some which also affect the "open time" or drying curve of the paints they are added to as well as their viscosity, but these are "side effects" or secondary considerations. If you only wish to thin your paint, simply add some turps and oil . . . that's a diluent, not a "medium". If you must have your paint dry quickly, add a siccative such as cobalt, manganese or lead linoleate.

Some guidelines:
Adding more than 20% by volume of any medium to oil paint is risking the ultimate failure of the paint film in some form or other.
Most mediums should be considered "end game" materials to be used in the final layers of paintings built up in multiple layers (underpainting, overpainting, and overglaze) and should be used sparingly if at all in the underlayers in order to abide by the "fat over lean" principle of sound painting practice.
Use different mediums for different purposes in different layers and for different effects. No medium is a "one size fits all".

Now to your question about walnut oil and alkyds. Walnut oil is a suitable drying oil, and makes good paint. From the beginnings of oil painting, it was not preferred, however, but was used in the Mediterranean countries for reasons of availability and lower price. Cennino Cennini who wrote what is possibly the first compendium of oil painting materials and techniques noted that the paint film walnut oil produces is neither as strong nor as flexible as linseed oil, and pronounced on the superiority of linseed over walnut oil as a paint vehicle.

Walnut oil is less viscous and imparts a certain "quickness" or slipperiness to paint, making it "fast" in the brush. It is nearly water-clear, so whites or blues out of the tube appear more "pure" than colors ground in linseed oil which is slightly yellow even when bleached pale. M.Graham and Robert Doak are two colormen who make excellent paints ground in walnut oil.

Alkyd resin is a synthetic compound made by combining an alcohol with an acid (originally designated "al-cid" when it was compounded as an automotive coating in the 1930's). Alkyd mediums are now touted as substitutes for Congo Copal and Maroger's Medium, and behave more or less like the real thing. So long as one paints "a primier coup" i.e., wet-in-wet, completing the painting before any passages become touch-dry, there's not much about alkyd mediums to find fault with. Alkyds (and other synthetics)have almost entirely supplanted the use of natural resins and oils in utility coatings and varnishes for industry and home use, and their durability is very good.

Problems arise when a painter who paints using layered techniques chooses alkyd mediums. Delamination is a certainty unless paint layers which have become touch-dry are mechanically abraded (sanded, or scoured with a Scotchbrite pad) to provide a mechanical "key" for the next coat of paint to adhere to. The presence of natural oils exacerbates the tendency of alkyd films to delaminate, and often dry layers can actually feel quite "greasy" to the touch.

The nature of easel painting rather precludes observing delamination in all cases (which would become readily apparent painting a wall or an implement, when lack of wearability would be demonstrated through normal handling) For this reason, some may in all honesty gainsay the certitude that "alkyds delaminate". In this case, one's own studio tests can prove beyond doubt the truth or falsity of recommendations one reads about.

At last, referring back to my analogy of the "bad oyster" in the varnish thread:
When the air becomes blue with vehement pronouncements on the inadvisability of using one or another medium, it is well to recall the nature of materials which are the products of plant growth and agriculture. Like foodstuffs, not all materials commonly called by a popular name are the same, exact species (consider the variety of types of apples, for example).

Like the oyster, not all materials of the same species arrive at the marketplace or the manufactury at the same level of quality, and lastly, there is no material under the sun which cannot be misused to the point of failure through accident, carelessness or ignorance . . . regardless of its quality.
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Old 11-29-2008, 06:50 PM   #2
Jennifer Bogartz Jennifer Bogartz is offline
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I think I've made a mistake...

I've been using Liquin to experiment with glazing, I'm copying a master painting (Caravaggio). At first I just used a little Gamsol, walnut/alkyd medium and paint. Then I just used the walnut/alkyd medium and paint. The paint started to bead up when I tried to glaze over it so I switched to Liquin and paint. I didn't sand in between layers. I did mix the Liquin in with some paint, more than 20% medium I think. I also dabbed my brush into the liquin and mixed it with the paint. After reading what you wrote about mediums, I think I used bad painting methods.

I'm used to working alla prima with just paint and walnut oil but wanted to gain some experience with working in layers and glazes. How do I do that with sound methods that won't delaminate?

Also, with regards to working fat over lean, is Liquin considered fat or lean? If it dries faster than paint straight out the tube than can I use paint straight out of the tube over it? Should I ditch the Liquin?

I appreciate any feedback you have.
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Old 11-29-2008, 11:33 PM   #3
Claudemir Bonfim Claudemir Bonfim is offline
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Quote:
Originally Posted by Richard Bingham
What a medium is NOT:

It is not a belief system, a talisman or a religion that will give the user the powers of a Raphael or a Velasquez.
LOL...

That's right, some artists think that by using the same pallette or medium used by some old master they will achieve the same results.
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Old 11-30-2008, 02:25 PM   #4
Michael Georges Michael Georges is offline
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Jennifer:

If you add a "drying agent", in the case of Liquin, cobalt dryer to your paint, IMO you sort of negate the whole concept of fat over lean. Fat over lean principles apply when you are applying paint in layers where you want a bottom layer to be dry before you put another over - or at least you want them to dry at a consistent rate with each other to prevent cracking of top layers from a bottom layer drying slower.

Drying agents like cobalt or manganese or lead circumvent that process by making the layers dry faster and more consistent with each other.

You will find differing opinions on Liquin, and on how to glaze. The beading is interesting and I suspect is is due to a slick surface combined with the use of mineral spirits (gamsol) over turpentine. Again, IMO, mineral spirits are great for cleaning brushes, but I don't bring it anywhere near my paint as I don't believe it works in the same way that turpentine does.

EDIT: I believe Richard Bingham understands this MS/OMS vs. Turps concept much better than I do and perhaps we can convince him to explain it. I remember reading the case for the differences on Cennini and thinking that it made a lot of sense.
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Old 11-30-2008, 05:48 PM   #5
Richard Bingham Richard Bingham is offline
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Michael, the concept of "fat over lean" is actually something quite apart from how dry an underpainting layer is before continuing to overpaint, although that is certainly a factor in painting in a layered technique.

Essentially, "fat" paint contains a lot of vehicle . . . that can mean its "chubbiness" results from the addition of mediums of all descriptions, but "fatness" is also a function of the pigments involved. Certain pigments, (e.g. ivory black) are very absorptive, requiring a lot of oil to reach desirable working consistency as paint. Other pigments, notably most earth colors, have a low absorptive index, and so they are naturally "leaner".

The relative dryness of underlayers as one progresses with a painting is a factor in good painting practice. Continuing to work on layers that are touch-dry but not dry all the way through promotes build-up of paint layers that become a homogenous unit by forming a chemical bond through solvent transfer.

It's a good idea in general to avoid using cobalt or manganese siccatives in particular, because these compounds promote rapid drying from the surface inward, causing paint to "skin over" and effectively sealing off paint that is not yet thoroughly dry. The difference in drying rates and shrinkage can cause crazing and other defects.

The reason "good" turpentine is a better solvent choice than MS or OMS (both are petroleum distillates similar to kerosene, but more highly refined) is that hydroxides in turpentine react with acids present in linseed oil. The reaction binds ambient oxygen, which promotes thorough drying of paint films from the "inside out" as well as from the top down.

Turpentine is in trouble. In many circles, it is seen as a horrible, smelly, toxic substance akin to nuclear waste, while OMS is tolerated as being "safe" on the basis of being odorless . . . which is rather a dangerously uninformed point of view, since both turps and mineral spirits have a near identical vapor pressure. This means an open container of either will emit the same amount of hydrocarbons into the studio atmosphere through evaporation. Safe practice demands that all solvent containers be covered, and that studios have adequate ventilation.

For the past couple of years it has been nearly impossible to obtain "good" turpentine, i.e., the stuff that is distilled from tapping the gum of living conifers, a process similar to collecting maple syrup. Pure Spirits of Gum Turpentine is water-clear, and smells clean, like a pine forest after a rain.

What has supplanted "good" turpentine in hardware and paint stores is a foul-smelling distillate produced mostly in the orient by grinding stumps, limbs, slash and forest waste and steam-cooking the mash to obtain a liquid with the chemical properties of pure spirits of gum turpentine, but with other adulterants and a fair amount of free water. It is the camp-follower of deforestation, reeks of creosote, and should NOT be used at the easel for any purpose.
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Old 12-01-2008, 11:46 AM   #6
David Clemons David Clemons is offline
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It's a pity that art supplies don't come with instructions or user manuals with an end chapter on troubleshooting or 800 numbers to call. I doubt it would improve things much if they did.
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Old 12-01-2008, 02:05 PM   #7
Allan Rahbek Allan Rahbek is offline
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I have made all the mistakes mentioned so far.

My Mona Lisa copy from 1969, one of the first paintings I ever did, is very dark because of too much medium and "refreshing" layers of varnish over time. I will do almost anything to avoid repeating that mistake.

I have settled on the use of what is called "Mayers Medium" which concist of : 5 parts Turpentine, 1 part Stand Oil and 1 part Dammar. This is not a quick drying medium but it does the trick for me. The mixture of 5 turps to 1 Stand Oil vill delute the paint without making it matte and the Dammar will speed up the drying a bit.
I think that it is the best compromize because it works for me, especially because it is now possible to buy Flake White here in Denmark ( Flake White, known to be a fast drier)
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Old 12-13-2008, 03:29 PM   #8
Richard Bingham Richard Bingham is offline
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"Mayer's Medium" is what has been universally used in university art departments for over a generation. What has not been taught is an overview of sound painting methods and the nature of materials. While quite innocuous as a "medium", it's commonly used simply as a diluent in the absence of better instruction.

Information on the broad variety of handling characteristics paint additives (that may be properly termed " painting mediums") can present has been sorely lacking where art instruction has abrogated systematic teaching of the craft aspects of applying and handling paint in favor of promoting a "self expression" unfettered by considerations for the physical realities which materials in general present.

The presence of damar in the "Mayer Mix" is qustionable, as it adds nothing to the handling character of paints that varying proportions of oil and turpentine do not. Stand oil affects the nature of paint films more dramatically than damar, and may be termed a "medium" when used instead of an untreated raw linseed oil.

The recipe for Mayer's three-part recipe is perennially suspect, as more often than not, damar retouch is used, which is already diluted over 50% with additional turpentine, to the point the resin and oil are so over-extended their presence is moot, the effect being negligible if not unnoticeable.

To reiterate, painting mediums are not diluents; they are not siccatives.

Turpentine alone will reduce the viscosity of tube paint, as well as accelerate drying. Adding certain proportions of oil will prevent the paint from being underbound.
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Old 12-13-2008, 06:35 PM   #9
Allan Rahbek Allan Rahbek is offline
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I believe that it makes sense to name "Mayer's Medium" a medium because it is a mixture of oil and turps used to mix into the paint to control the workability of the tube paint.

I work mostly wet into wet over a thin wash of paint diluted with Vegetable Turpentine.

The "M's M" works better than using only turps when it is used as diluent in the paint.

The problem with "only" turps is that it makes the paint more lean and, in addition, it's difficult to control the viscosity of the paint using only turps, it becomes easily too thin and the turps evaporate too fast. The Stand Oil compensate for those three disadvantages.

It is correct that it's primarily for thinning purposes that I use it, but I find that it fairly neutral to the original tube paint composition.

When the painting is dry I will varnish it with a removable varnish.
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Old 12-14-2008, 12:37 PM   #10
Marvin Mattelson Marvin Mattelson is offline
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Allan, personally, I avoid using Damar for any purpose whatsoever and make this a major point when advising my students of prudent choices for the best archival painting methods. Damar yellows and gets more brittle as it ages.

Unlike linseed oil, in which the yellowing can be reversed upon exposure to natural light, Damar's effects are irreversible. When used as a final varnish it becomes increasingly more difficult to remove and requires extremely powerful solvents to accomplish this. Many a great painting has been ruined through ill fated attempts at it's removal when used as a varnish. I just don't see the up side.

The vast majority of old master paintings have no evidence of Damar, or any resin for that matter, in the paint layers. From the 18th Century on there was a lot of speculation going on regarding the make-up of artist's mediums, particularly regarding artists from the 17th century.

Fortunately, modern science has disproved the bulk of this conjecture, so we can make better decisions than far too many of our forbearers.
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