A question was posed about Studio Safety (oil paints) and it isn’t a question easily answered. It depends on many factors including your studio set up as well as painting medium(s) that are being used. Also, there isn’t just one “go to” person to ask. I reached out to Scott Gellatly, Artist and Product Manager at Gamblin Artists Colors and he provided some valuable information and resources.
How do I choose and manage solvents in our oil painting studio? (this is an excerpt from a Studio Safety Guide for Schools that Scott is working on)
Solvent is traditionally used in oil painting for a few different reasons. Solvent is used for brush and studio clean-up, as well as used in moderation to thin oil colors from the tube.
Solvent is also a component of most painting mediums used to alter the viscosity of oil colors and speed drying. In making mediums, the solvent is mixed with a drying oil (i.e. linseed oil) and/or a resin (traditionally dammar resin or contemporary resins, such as soy-based alkyd).
Gamblin’s approach to painting mediums is to formulate a range of contemporary mediums based on alkyd resin, as it allows us to create mediums with the mildest form of odorless mineral spirits: Gamblin Gamsol.
There are hundreds of different types of solvents in the world – all with unique properties and applications in various industries. A variety of different solvents have been incorporated into oil painting studios over its history. Not all solvents are created equal. Below is information on what makes Gamblin Gamsol uniquely qualified to be the standard for studio safety in classrooms and home studios.
A solvent’s safety is a factory of its evaporation rate, permissible exposure level and the ventilation in the workspace. These factored are discussed below.
DEFINITION OF AN ARTIST’S SOLVENT
*The Artist’s Handbook of Materials and Techniques by Ralph Mayer and The Painter’s Handbook by Mark Gottsegen are the two definitive books on painting materials published in America. They both define the working properties of an ideal artist’s solvent the same way.
An artist’s solvent should:
- Evaporate completely
- Evaporate at a uniform rate
- Have no effect on dried paint layers
- Be chemically inert to the materials with which it is used (i.e. have no chemical reaction)
- Mix completely with the materials with which it is used
- Have no toxic vapors
- Evaporate entirely from the dried paint film within a reasonable amount of time
Many solvents on the market satisfy some of these requirements. Gamsol meets all of these requirements when used as recommended.
Gamblin Gamsol odorless mineral spirits balances both performance and safety like no other artist’s solvent on the market.
GAMSOL VS. OTHER SOLVENTS
Gamsol allows painters to work in traditional and contemporary techniques without compromising artistic possibilities, permanence, or your well-being. Gamsol is also reusable, and non-toxic when used as recommended.
Most solvents available to artists are produced for the industrial paint industry where solvent strength and low cost take priority over safety. Gamsol is different. It comes from a family of materials used in products that come into more intimate contact with the body: such as cosmetics, hand cleaners, and cleaning food service equipment.
For an artist, there are a number of factors to consider when judging a solvent’s safety. Aromatic solvents are the most harmful type of mineral spirits. Gamsol is an odorless mineral spirit which has all of the aromatic solvents refined out of it – less than .005% remains. In addition, Gamsol has a slow evaporation rate, a high flash point, and is not absorbed through healthy skin.
Unlike other solvents, Gamsol is readily biodegradable and contains no Hazardous Air Pollutants or Ozone Depleting Compounds.
Evaporation Rate Testing
One key metric in determining the inherent safety of a solvent is the rate in which the solvent evaporates. The chart below documents the results from testing three common solvents: turpentine, mineral spirits and Gamsol. A tablespoon of each solvent was placed on a 3 ¼” wide metal lid, and subsequently placed on three different scales to measure the amount of time (in days) in took the solvent to evaporate.
Within the first 48 hours of this test, approximately 94% of the turpentine and the majority of mineral spirits had evaporated. Gamsol’s evaporation was slow and steady over the test’s nine-day period.
This test was repeated to look at these same three solvents within an eight-hour time period:
During the eight-hour period, 77.6% of the turpentine evaporated, 46% of the Mineral Spirits and only 13.3% of the Gamsol.
** Note on above testing: During the 9-day solvent evaporation test, the average temperature in our lab in Portland, OR was 64 degrees F. During the 8-hour test, the average temperature was 75 degrees F.
Again, the above test was prepared by placing a tablespoon of each solvent on 3 ¼” wide metal lids. When approximately eight fluid ounces of Gamsol were placed in a commonly-used Silicoil Brush-Washing Container, only .29% of Gamsol evaporated when tested over an eight-hour period.
Flash Point Comparison
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source (i.e. match or flame).
Below is a listing of common solvents, along with their corresponding flash points:
Mineral Spirits: 100.4°F
“Odorless Mineral Spirits”: 110 – 120°F
Recommended uses for Gamsol
Thinning oil colors: Gamsol beautifully thins oil colors. A little goes a long way; oil colors relax immediately when a little Gamsol is added. Since Gamsol evaporates completely, no sticky residue is left behind that could compromise the drying or strength of paint layers.
Modifying painting mediums: Gamblin Galkyd painting mediums are formulated with Gamsol, so they readily accept Gamsol as a solvent. Gamsol should not be added to traditional painting mediums containing dammar, copal, mastic resins. They require stronger solvents such as turpentine. Adding Gamsol to oil painting mediums is an effective means of modifying the oil (“fat”) content of these materials to allow artists to explore indirect/glazing techniques.
Studio Clean up: Gamsol is great for general studio clean-up of brushes, palettes, palette knives and other tools. As a brush cleaner, it effectively removes oil colors from brushes to allow for clean mixing and application of color.
What are the guidelines for air exchange in the oil painting classroom using Gamsol and Gamblin Oil painting mediums?
According to the recommendation of environmental hygienists, studio air should be changed ten times per hour.* Normal HVAC systems in most buildings and homes will allow for adequate air exchange using Gamblin oil painting materials.
Please keep in mind, though, that solvents used in conservation labs are much stronger than Gamsol.
Just to “round out” the conversation on Studio Safety and painting mediums, please also refer to our recent Studio Notes newsletter on Solvent-Free Painting techniques and materials.
Studio Notes newsletter – Solvent Free Painting Techniques and Materials
*The Artist’s Handbook on Materials and Techniques, Ralph Mayer
Air purifier, recommendation that we got from the Conservation Science community