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Old 11-22-2008, 07:56 AM   #21
Claudemir Bonfim Claudemir Bonfim is offline
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Quote:
Originally Posted by Jennifer Bogartz
Thank you for answering my questions. Why is it best to avoid organic varnishes like the one made out of egg white and salt?
Because that is not a strong varnish, yellows faster than the others and can be really messy to apply. The good thing is that it is non toxic, but if you go outdoors you won't have problems using retouch varnish. The final varnish can be used in your studio (if you are using brushes).

A good example of the quality of current varnishes is the one used on Rembrandt's Night Watch. A crazy guy threw acid on the painting (and that was the second time the painting was attacked), immediately after that a security guard started removing the acid with destilated water and fortunately the acid didn't reach the painting, it only scratched the varnish surface (of course there were thick coats of varnish). The results woundn't be the same if that happened to egg varnish.
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Old 11-22-2008, 07:58 AM   #22
Claudemir Bonfim Claudemir Bonfim is offline
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Ps.

Egg varnish "can" go rancid if not mixtured correctly.
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Old 11-24-2008, 09:31 AM   #23
Amanda Grosjean Amanda Grosjean is offline
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Claudemir,

This is off topic again but thank you for sharing that info on the Mona Lisa. What you discussed with the Raphael images was really interesting. If you ever want to start a new thread on damaged paintings I would be happy to learn about it and I'm sure many others on this forum would as well.

Thanks!

Amanda
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Old 11-24-2008, 10:57 AM   #24
Claudemir Bonfim Claudemir Bonfim is offline
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Quote:
Originally Posted by Amanda Grosjean
Claudemir,

This is off topic again but thank you for sharing that info on the Mona Lisa. What you discussed with the Raphael images was really interesting. If you ever want to start a new thread on damaged paintings I would be happy to learn about it and I'm sure many others on this forum would as well.

Thanks!

Amanda
Fine, as soon as I find some time.
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Old 11-28-2008, 04:41 PM   #25
Richard Bingham Richard Bingham is offline
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While responses to this thread contain a lot of good information, there are also a number of errors, misconceptions and suggestions which are not entirely sound if taken as unqualified advice.

At the risk of starting a flame war, I presume to address them on the basis of 50 years experience painting in oils, and dealing with a wide variety of paint materials of all types:

Quote:
Originally Posted by Claudemir Bonfim
. . . oil paint never dries, it solidifies with the addition of oxygen molecules, and that's why the paint yellows with time. If the painting is varnished, then . . . the varnish yellows first . . .

Avoid organic varnishes!

. . . Paintings in museums receive very thick coats of varnish . .
One problem in discussing materials and methods is first to define the terms. Most people understand paint to be "dry" when it can no longer be manipulated, lifted from the surface, or malleable when handled. Claudemir is correct to state that the process of oxidation continues in oil paint films for a long time. However, for the purpose of addressing the question of a "final varnish" for a painting, it is only necessary for a paint film to reach a state where free volatiles have evaporated. As further noted, the length of time for a painting to reach this condition depends upon the thickness of the films and also ambient conditions.

The ultimate yellowing of oil films is a chemical reaction which has nothing to do with the oxidation of polymerized oils and/or resins. Curiously, the nature of linseed oil paint films is to yellow and darken when deprived of ambient sunlight. Humidity exacerbates the yellowing process, which is readily demonstrated by the oil itself, even before being incorporated into paint; it becomes increasingly lighter when exposed to sunlight.

A painting stored in a dark, damp place may yellow very noticeably in a relatively short time. Exposed to normal room (sun)light, the yellowing will reverse. The oil films cease to be reversibly reactive when the paint film has reached a certain point in the aging process . . . usually several decades.

Yellowing of the varnish films is a process independent of reactions taking place within the painting. Many old paintings have been restored to a state nearing their original condition when multiple layers of varnishes applied through the centuries (and the dirt, dust and smoke they contained) were removed by conservators. The most famous example was when Rembrandt's painting "The Night Watch" was restored. It had been referred to by that popular name for a great many years, when in fact, it is a daylight scene. (proper title, "The Company of Frans Banning Cocq and Willem Van Ruytenburch )

All solvents, vehicles, oils and resins generally associated with oil painting are "organic" in the sense of the definition of "organic chemistry".

Modern conservation methods find the old practice of applying numerous heavy coatings of varnishes of various compositions anathema to preservation.

While the wikipedia link provided is a good general-knowledge overview of materials which the term "varnish" comprises, it has little or no practical application to the especiality of oil painting or the preservation of oil paintings. For that matter, linseed oil alone is, by definition, a varnish in itself!

Quote:
Originally Posted by Marcus Lim
. . . actual fact is the painting is still 'growing' inside the painting . . . varnish too early results in serious cracking problems . . . think Bruce Banner ripping his clothes off when turning into a hulk . . .
Marcus, the principle is correct, but you have it reversed. As paint films continue to dry and give up their volatiles, they shrink They do NOT "grow". Problems with cracking and crazing may be caused by violating the "fat over lean" principle when making the painting. If thin, faster drying (lean) layers are applied over heavier, slow-drying (fat) layers, the lean layer will shrink or embrittle over a soft layer which is not shrinking. Think of Bruce Banner watching the surface of a mud-hole crack in a net-pattern as it bakes in the sun!

Varnishing too soon may cause cracking, but a more likely result (for damar or mastic at least) will be that the varnish will become incorporated into the painting itself through the process of solvent transfer, negating the advisability of having a "final varnish" be a removable, protective layer.

Quote:
Originally Posted by Michael Georges
. . . I have varnished paintings that were more than 25 years old . . . used . . . good turpentine to wipe the whole painting down . . . I add a bit of wax medium to my varnish . . . more of a satin finish.
While a painting 25 years old could very likely suffer a wiping with turps (or any other solvent) without visible damage, most conservators would cringe at the thought. Usually, the first line of cleaning is to dab the painting surface with surgical cotton dampened in distilled water. Of course, extreme cases would require something more, but in general, it's not a good idea to wipe down any painting with solvents prior to varnishing.

Adding wax to a "final varnish" is questionable on a number of levels. First would be the question whether the varnish chosen and wax are compatible. Damar and pure beeswax is a compatible mixture. The problem is the result is a varnish that is malleable, attracts dirt in its own right, and is much softer than damar alone.

In choosing a material to use as a final varnish, two requirements are inviolable: 1. The varnish should provide protection 2. The varnish should remain indefinitely soluble in its parent solvent to enable its ready removal at a future date.

A better long-range tactic would be to apply a suitable material as a final varnish, and regardless of its composition or final glossiness, a satin finish may be readily achieved by the application of a wax layer that is not part of the varnish

Quote:
Originally Posted by Claudemir Bonfim
Some guys like Damar, I personally think that it yellows too fast, but other[s] . . . haven't experienced the same problem, I think tht's due to climate differences . . .
Here, Claudemir addresses a major problem we encounter in discussing materials and methods. The traditional materials of oil painting have always been open to the question of the nature of the source, and the quality of the material. Resins are especially problematic, as those commonly associated with oil painting (damar, copal, mastic); each is a generic term encompassing a wide range of similar species, each with quite different individual qualities and properties. Sometimes it depends where certain species are grown.

What works well for me in the dry, cool climate of the high desert US west may very well cause specific problems in the humidity of tropical Brazil ! This is why it is so necessary for painters to become intimately acquainted with their materials, and knowledgeable by running their own tests. It's fascinating how closely processes in the studio and the kitchen are related! About the relative quality of materials, I could never understand how anyone could dislike oysters . . . until I was served a "bad" one! Simlar considerations apply to the painting materials we prefer!

Quote:
Originally Posted by Jennifer Bogartz
. . . Why is it best to avoid organic varnishes like the one made out of egg white and salt?
Our modern "just run down to the store" culture primes us to be surprised at such a suggestion as using egg-white for varnish. Anyone who has left the dirty dishes in the sink overnight quickly realizes that a number of food-stuffs are very tenacious adhesives and coatings . . . In earlier times, folks were intimately acquainted with where their lunch came from, and readily observed how blood, milk, eggs, and a number of other "food" items could provide substance for "paints" of different types and applications.

If you have ever encountered the "beauty secret" of using egg-whites in a facial treatment (to eliminate wrinkles?) you can readily understand how using egg-white "varnish" on a painting might not be the best choice . . . shrinkage is extreme, the film is brittle, and although Claudemir refers to being able to remove it easily with water, I wonder . . . after all, eggs (the yolk) are the major ingredient in "egg tempera" . . . a paint choice that's far more stable and permanent than oils! (ever had your car "egged" ??)
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Old 11-28-2008, 07:28 PM   #26
Claudemir Bonfim Claudemir Bonfim is offline
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I was missing your comments here Richard.

I prefer to use a mix of gloss and mate varnish, what about you?


Ps. I have never had my car "egged".
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Old 11-28-2008, 10:45 PM   #27
Richard Bingham Richard Bingham is offline
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I'm awfully old-fashioned. I use a 6:4 mixture of damar and mastic, I make up the varhishes in the studio using good turpentine and the best quality resins at a 5# cut (proportions: five pounds of resin to a gallon of turpentine)

This mixture is easier to manipulate than damar alone. I apply the varnish with a 2" badger sash brush and "lay off" the surface with the tip of the brush as the varnish tacks up to eliminate a high gloss.

I've heard a lot of good things lately about Gamvar, which is a synthetic varnish (I believe methylacrylate resin). The resin is dissolved in mineral spirits, and is reported to remain dependably water clear over time, as well as readily removable in MS indefinitely. It sounds good, but I haven't tried it yet myself . . . mostly because I don't see a pressing need to replace a method I've found suitable. Those who have tried it report that it doesn't lend itself to manipulation in application, so what you see is what you get!

I'm glad you haven't been "egged" ! (Maybe vandals in Brazil have better sense?)
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Old 11-28-2008, 11:35 PM   #28
Jennifer Bogartz Jennifer Bogartz is offline
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Richard, thank you very much for your insight. You mentioned that artists can run their own tests on materials. How would I go about testing the materials I'm using? I am currently using walnut oil, walnut/alkyd oil, and liquin as medium (not all at once). I've heard some negative things about alkyds and liquin such as delamination and have not worked with them long enough to see those kinds of problems in my work. I'm in the process of researching varnish and can see the benefit of testing the material before committing to it. Does an artist need to try many different mediums and varnishes in order to become well acquainted with them?
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Old 11-29-2008, 07:50 AM   #29
Claudemir Bonfim Claudemir Bonfim is offline
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Quote:
Originally Posted by Richard Bingham

I'm glad you haven't been "egged" ! (Maybe vandals in Brazil have better sense?)
Well, it is not common to have your car attacked by vandals here, in fact, it is very rare, but when it happens during some sort of manifestation, things go really bad.

Well Jennifer, I think Richard will answer your question soon, but meanwhile I'd like to tell you that mediums are something very personal. It depends on your way of working. Some mediums accelerate the drying of paints, others slow down. You should watch Daniel Greene's video "Erin", in this video he addresses this subject in detail.

If you don't have access to the video, we can discuss it here on in another thread.

You mentioned Walnut oil, that's wondeful but adds a lot to the drying time. In my Country people don't have the culture of patience to sit for long sessions, so I use my mix of 1 part of stand oil e 4 parts of odorless mineral spirits, this medium accelerates the drying time. I also use Titanium white of flake white, which get dry a lot faster than zinc white.

You will have to find your own recipe to your medium, but I also avoid the ones with bad reputation.
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Old 11-29-2008, 02:44 PM   #30
Richard Bingham Richard Bingham is offline
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Jennifer, for an artist to test materials in the studio, one realizes first off that we don't presume to have a command of either organic chemistry, nor of laboratory grade procedures and equipment.

The first test is quite naturally, one of a simple "hands on" assessment. Does the material "do" what you want it to? Does it handle to your liking?

Tests for permanence are rather more subjective, as there may be a great number of variables which will be out of one's control as soon as a painting leaves your possession. I rely on a rather "dumb brute" method for testing my materials, simply subjecting test samples to outdoor weather. I place test samples of painting supports, paints, mediums, varnishes, etc. outdoors on the weather side of my studio, and leave 'em there. Between exposure to sunlight, temperature variations from -20F to over 100F, rain, snow, hail, sleet and frosts, a pretty good picture of a material's failure modes emerges. Naturally a painting would never be subject to that kind of abuse under normal conditions, but weather provides a semblance of accelerated aging. Naturally, it's not going to cover all the bases.

Learn as much as you can about materials from reading. To keep it very simple, my favorite book on that subject is Frederick Taubes' "Studio Secrets" alas, now out of print. Unlike a number of latter-day self-proclaimed experts on the subject, Taubes was a practising studio artist who based his methods on what is known of traditional "old master" technology, and as an entrepeneur who marketed painting materials and mediums was actively involved "hands on" in his business. He wrote the technical column in American Artist from 1942 until well into the 1950's, and taught materials and methods courses in seminars he gave around the country.

I think every artist who paints in oils should own a copy of Ralph Mayer's "The Artist's Handbook of Materials and Techniques". It contains a lot of sound, basic information, although it is overly ambitious in scope, and suffers from the fact that Mayer was more an "armchair" type who relied heavily on "hearsay" and recapitulating information from other sources as opposed to verifying the book's contents through his own working experience.

Beyond that, discussing materials and methods with your peers is almost always instructive (one way or another) but can be a minefield of errors and incomple information and bad practice. One should have a clear working knowledge of painting materials and procedures and a means for testing all the ideas which abound, rather than blindly following anyone's "prescriptions". It sounds forbiddingly complex, but hey, it's not rocket science, and the basics are very simple. All the complexities are either overlapping redundancies, or extrapolations which can fall back easily upon the knowledge of basic, sound painting practices for clarification.

Since I'm feeling reckless, (read stupid?) I think your questions about mediums would be better addressed in another thread, which I'll open in response to them. Claudemir wisely notes that the subject of painting mediums is one which is very personal with almost everyone who paints in oils, and has caused some dandy knock-down-drag-out flame wars on art fora as well as in person, when artists meet.
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