F.A.Q.s: Oil Paint

• I love painting in oils but the fumes really bother me. What are my options?
  
• Do I have to varnish my oil painting? How long should I wait, and what should I use?
  
• How do I select my kit for painting en plein air?
  
• I want to experiment with oils mixed with other media. Should I be aware of any potential problems?
  
• My painting is showing some signs of cracking and peeling. What caused this?
  
• I have an old painting I want to restore. What should I use?
  
• Why do some colors cost so much more than others? What does the word “hue” mean?
  
• Can I paint with oil on paper?
  
• The school where I teach is considering adding oil painting to the curriculum, but the administration is worried about safety issues. How can I address this so we can use oils in our current facility?
  
• What is Retouch Varnish used for?

Q: I love painting in oils but the fumes really bother me. What are my options?
A: Most artists who complain of trouble with fumes from oil paint are bothered by gum spirits of turpentine. Turpentine is known to produce allergic sensitivity and respiratory irritation, which can worsen over time; also, turpentine exposure can evntually produce sensitivity to other materials. The best alternative is odorless mineral spirits (Item No: 14114) (OMS), which has been refined to remove volatile odor-producing components. OMS does not cause allergic sensitivity; in addition, its lower rate of evaporation and higher flash point make OMS a safer choice in the home studio as well. Mineral spirits does not work as well as turpentine for making some resin varnishes, however, nor does it accelerate the drying rate of oils like turps.
Oil of spike lavender and rosemary distillates have been used interchangeably with turpentine as thinners and to make spirit varnishes. According to materials safety documentation, there is very little data to suggest turpentine hazards are associated with oil of spike lavender. This is probably due to considerably less use in industry compared to turpentine, but as oil of spike lavender contains many of the same compounds present in turpentine (alpha-pinene and beta-pinene) it may not be completely benign.

Q: Do I have to varnish my oil painting? How long should I wait, and what should I use?
A: While many artists choose not to varnish finished paintings, there are many compelling reasons to do so. Varnish protects the picture from dirt and damage and makes cleaning safer and easier. Varnish deepens the appearance of dark colors and restores the wet appearance of the paint, so often a varnished picture better reflects the artist's original pictorial goals. However, a shiny surface makes it harder to light and photograph a painting, so matte varnish (Item No: 11408) may be a better choice in some instances. (Matte varnish is produced by adding wax, silica powder or some other matting agent to standard varnishes.)
A traditional oil painter's varnish, damar (Item No: 34342) is easy to make in the studio and simple to apply. Additionally, damar can be easily removed, as it remains permanently susceptible to solvents. However, the tendency of natural resin varnishes such as damar and mastic to eventually yellow and become brittle has led many artists to migrate to synthetic products. While some synthetic varnishes are subject to the same technical issues as traditional products, conservators regard solvent-based acrylic resin varnishes as the best choice for a final, protective application for oils. Back to Top.

Q: How do I select my kit for painting en plein air?
A: The unique challenges of painting in the field require a somewhat different approach in terms of selecting colors, mediums and supports. Panels are a great choice for painting outdoors because they are thin, durable and light. Sketch boxes and French field easels normally have slots in the lid to hold one or two wet, finished paintings on panel. Utrecht offers traditional canvas panels and professional-quality linen panels as well, primed and ready to accept paint.
In terms of which colors and mediums to choose, for plein air painting the goal is to have a compact assortment that allows easy direct mixing of any observed color. Select a small assortment consisting of a warm and cool of each primary, one or two greens (viridian and sap green are ideal), several earth colors (yellow ochre, burnt sienna and raw umber) and a large tube of titanium white or Utrecht white. Alkyd-based painting medium will help speed up drying; Utrecht Alkyd Gel (item 11412) is easy to dispense on the palette without a cup. Odorless mineral spirits is handy for rinsing brushes, but remember to bring a jar with a tight-fitting lid to store exhausted solvent for proper disposal later.Back to Top.

Q: I want to experiment with oils mixed with other media. Should I be aware of any potential problems?
A: Experimental techniques produce uncertain results. Sometimes the outcome can be desirable, but sometimes things just don't work out. By applying some basic understanding of your materials it's possible to really push the limits of your medium and get dramatic, surprising effects. In general oils work best on top of sealed surfaces with lower oil content, such as some glues or acrylic paint. Oils will attack unprotected cloth or paper, so sealing inclusions and collage elements in acrylic matte medium is a good strategy for permanence. An alkyd-based transition medium such as Utrecht Alkyd Painting and Glazing Medium (Item No: 11412) applied and allowed to dry before working in oils is recommended for best adhesion to acrylic underpaintings. Finally, when using unusual mediums with oil paints, make certain you are not using something that will impede drying such as mineral oil, petroleum jelly or animal grease. Use your intuition, be prepared to learn from the results of your experiment whether good or bad, and have fun!Back to Top.

Q: My painting is showing some signs of cracking and peeling. What caused this?
A: There are a number of reasons why a paint surface can fail, but most are attributable to painting leaner (oil-poor) colors on top of fatter (oil-rich) ones or fast-drying colors on top of slow-drying ones. For best results, paint should contain less oil in the first layers, followed by progressively more oil in subsequent layers. Also, avoid using fast-drying mediums such as alkyd on top of oil paint with no alkyd, especially fatter colors. Other causes of paint failure include poorly prepared grounds (unprimed board or paper), excessive use of catalytic siccatives (cobalt drier) and experimental or inappropriate combinations of mediums. Back to Top.

Q: I have an old painting I want to restore. What should I use?
A: If the painting is by your hand and recently painted it may be OK to attempt repair yourself. However, if you are considering repairing, restoring or even cleaning an antique picture, you risk damaging or destroying the painting by your efforts. Conservation and restoration is a highly skilled profession requiring years of study. Old paint surfaces are complex and delicate, and damage may take a bit of time to become obvious. You might do more good to just store and preserve the painting in its current state until you can determine its value and learn a bit more about what needs done. Professional restorers are always busy repairing botched restoration attempts, so there's no need to make them any busier! In general, we do not recommend amateur restoration of valuable art objects. Back to Top.

Q: Why do some colors cost so much more than others? What does the word “hue” mean?
A: Some brands of oil colors are more expensive than others, but this may be determined by retail markup, country of origin and other factors not directly related to quality. Utrecht Artist's Oil Colors are a great bargain because you can purchase them directly from the manufacturer, but despite the low price our paints equal or exceed other national brands in tint strength, permanence, workability and all other important qualities. Within a given brand of paint there can be some difference in price from color to color, as well. This is not necessarily an indication that cheaper colors are of lower quality, though. “Series one” colors are often among the most brilliant and permanent, but may be safer or less labor intensive to manufacture, or the pigments may be more abundant. For the most costly colors such as cadmiums and cobalts most brands include a “hue” equivalent. The term “hue” indicates that the paint does not contain the genuine pigment, but is mixed from less costly or less toxic alternatives to produce the same mass tone as the genuine article. Hue equivalents generally do not perform as well in mixtures as genuine single-pigment colors. Back to Top.

Q: Can I paint with oil on paper?
A: Oil paintings on paper require special handling to preserve their longevity, but the artist can take steps to ensure the permanence of their oils on paper. Heavier papers, especially 100% rag watercolor and printmaking papers are the best choices for this technique. A rigid, stiff paper offers the best protection from warp and dimensional changes which can cause cracking. Paper should be prepared with Utrecht Acrylic Canvas Size (Item 6326) to protect the support from acids in the oil vehicle which can attack and deteriorate cellulose fibers as well as to prevent the paper from absorbing the oil required for paint adhesion. Utrecht Acrylic Gesso (Item No: 5102) may also be used for preparing paper to accept oils. Back to Top.

Q: The school where I teach is considering adding oil painting to the curriculum, but the administration is worried about safety issues. How can I address this so we can use oils in our current facility?
A: Though the specifics of your facilities may be a factor, in general oil painting can be done safely by a large group of people in the ordinary classroom, as long as certain precautions are taken. Linseed oil, the vehicle for oil paint and also a common mixing medium, does carry risk of combustion when soaked into rags; this is true of all vegetable oils, including cooking oil. Oil oxidizes as it dries, producing heat, which can lead to spontaneous combustion of oily rags. For this reason, painting rags should be placed in a covered metal trash can containing water at the end of class and disposed of daily.
Solvent use should be minimized in the classroom; avoid techniques involving broadly applied solvent washes which produce a lot of vapor. The solvent of choice for the oil painting classroom is refined odorless mineral spirits (OMS). Unlike turpentine, OMS does not produce allergic sensitivity or respiratory irritation; its low evaporation rate means less fumes, which combined with its higher flash point means OMS presents a much lower flammability risk compared to turpentine. Students should be strictly required to use only approved brands of OMS; exhausted solvent should be collected in a tightly covered jar for reclamation (OMS can be allowed to clarify and reused once pigment residue has fallen out). Solvent use can be further reduced by use of non-toxic brush cleaners for rinsing brushes. If necessary, the palette can be restricted to exclude the most potentially harmful colors without impeding the ability to mix color effectively.
While some oil painting supplies may not be appropriate for enclosed spaces, the craft can be practiced in a safe, responsible way without impeding the learning process. By taking simple precautions and exercising control over the quality of materials brought into the classroom, a safe and healthy working environment can be easily maintained in most school facilities. Materials safety documentation is available for specific guidelines to use of individual materials. Back to Top.

Q: What is Retouch Varnish used for?
A: Retouch varnish (Items No: 11403, 11414) is used to restore the wet appearance of colors in layered or “indirect” techniques. It is also used to isolate one layer from another. Retouch varnish can be used for a thin protective coat on finished paintings not yet sufficiently cured for a thick, final varnish. Back to Top.

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