Portrait Artist Forum    

Go Back   Portrait Artist Forum > Paints, Mediums, Brushes & Grounds


 
 
Topic Tools Search this Topic Display Modes
Prev Previous Post   Next Post Next
Old 11-29-2008, 04:30 PM   #1
Richard Bingham Richard Bingham is offline
Juried Member
 
Joined: Jan 2006
Location: Blackfoot Id
Posts: 431
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.
  Reply With Quote
 


Currently Active Users Viewing this Topic: 1 (0 members and 1 guests)
 
Topic Tools Search this Topic
Search this Topic:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump

Similar Topics
Thread Topic Starter Forum Replies Last Post
Ludwig Deutsch Enzie Shahmiri Artists of the Past 22 01-05-2009 08:44 PM
A No-lead Maroger medium? Karin Wells Paints, Mediums, Brushes & Grounds 38 04-30-2002 11:48 PM
Painting grins Peggy Baumgaertner Techniques, Tips, and Tools 2 02-11-2002 10:14 AM

 

Make a Donation



Support the Forum by making a donation or ordering on Amazon through our search or book links..







All times are GMT -4. The time now is 06:58 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.