F.A.Q.s: Grounds & Gesso

• Should I dilute my gesso with water? It seems too thick to apply with a brush.
  
• How long do I have to wait before I can paint on a canvas prepared using Oil Priming White?
  
• Do I have to use gesso? I prefer the look of raw canvas.
  
• Should I gesso the back of my canvas as well as the front?
  
• Can I gesso over an old canvas to reuse it?
  
• Can I use house paint instead of gesso?
  
• What is “rabbit skin glue”? Do I use it with acrylic gesso?
  

Q: Should I dilute my gesso with water? It seems too thick to apply with a brush.
A: When priming with Utrecht Professional Acrylic Gesso (Item No: 5102) or Artist’s Gesso (Item No: 9000) it's usually necessary to dilute it a bit with water, to a thick cream consistency for easy application. However, Utrecht Studio Series Gesso (Item No: 9002) is ready to apply directly from the package without dilution. When priming with a flat knife, Utrect Professional Acrylic Gesso can be used full strength. For best results when priming with a knife, lightly moisten canvas with a damp sponge or spray bottle of water before applying the ground.

Q: How long do I have to wait before I can paint on a canvas prepared using Oil Priming White?
A: To ensure good paint adhesion and consistent application, when using Utrecht Oil Priming White (Item No: 13110) according to package directions (diluted 2 parts primer to 1 part thinner) allow the priming to cure 14 days before painting. The addition of Utrecht Alkyd Painting and Glazing Medium (Item No: 11412) to Priming White can permit use of newly primed canvases in about 2 days; use 4 parts Oil Priming White to 2 parts mineral spirits/turpentine to 1 part Alkyd Medium. Drying time may vary depending on the temperature and humidity of the studio. Back to Top.

Q: Do I have to use gesso? I prefer the look of raw canvas.
A: If you are painting with oils, it's necessary to protect canvas from direct contact with the paint. Acrylic colors can be used directly on raw canvas, but it will absorb a lot of paint. To preserve the visible appearance of the cloth support, prepare your canvas or linen with Utrecht Acrylic Canvas Sizing (Item 6326), which will offer protection as well as a slight tooth to promote paint adhesion. Back to Top.

Q: Should I gesso the back of my canvas as well as the front?
A: There is no benefit to applying gesso to the back of your canvas. Sealing the back may prevent curing of the paint film by blocking contact with air. Also, it may cause additional canvas shrinkage, imposing additional stress on the stretchers. For best results, apply Utrecht Acrylic Gesso only to the front of your canvas. Back to Top.

Q: Can I gesso over an old canvas to reuse it?
A: Acrylic-based primers do not adhere well to oil paint, so it's not a good practice to apply gesso over any oil paint, even completely dry paint. To reclaim materials from old oil paintings, it's best to just reuse the stretchers and start with fresh canvas. Important commissions and major works are best done with fresh canvas. However, for thrifty reuse of old oil canvases for sketches and experiments, the old paint can be sanded down and the surface primed with lean, lead-based white oil. (After sanding, wipe away any remaining dust with a cloth and a small amount of odorless mineral spirits.) Lead-based white has good hiding power and provides a good priming surface for new work, but some texture of the original image will probably be visible as pentimenti. Be aware that some colors such as Prussian Blue, Alizarin Crimson and Phthalo-based hues can, over time, migrate from the original painting through subsequent layers and produce ghost images. Old acrylic paintings can be re-primed with acrylic gesso if the texture is not too intrusive, or sanded if necessary. Do not sand any painting that may contain hazardous pigments; always wear a filter respirator when sanding any painting, and take care to clean up all dust immediately. Back to Top.

Q: Can I use house paint instead of gesso?
A: Utrecht Professional Acrylic Gesso (Item No: 5102) is expressly designed to provide superior paint adhesion and protection for canvas as well as optimal appearance of colors for the long-term life of your work. Ordinary house paints and primers, while of good quality for their intended purpose, are not made to last to the standards of permanent painting. Synthetic latex may be similar to acrylic emulsion, but the acrylic selected for artist's primer is specially chosen for permanence and other properties important for effectiveness with artist's paints. Latex emulsion in house paint provides flexibility but with the sacrifice of longevity. Extreme flexibility is not necessarily an asset in preparing canvas, either; some rigidity is needed to maintain a proper stretch, as gesso is both sizing and priming in one. Finally, it's important to note that all varieties of Utrecht Acrylic Gesso are generally less expensive than all but the cheapest house paints and primers, so there really seems to be no compelling reason to substitute for genuine professional gesso. Back to Top.

Q: What is “rabbit skin glue”? Do I use it with acrylic gesso?
A: Rabbit Skin Glue (Item No: 34361) (RSG) is a protein-based sizing and adhesive for cloth painting supports. RSG protects canvas fibers from the damaging acidity of drying oils and imparts stiffness to the canvas, maintaining a tight stretch which minimizes stress on the paint film as it ages. RSG is used under oil and alkyd primings and traditional glue gesso, never under acrylic gesso. The water in acrylic gesso will soften RSG causing crazing of the primer. Rabbit Skin Glue is hygroscopic, meaning it will absorb moisture from the air, causing it to swell under some conditions; for this reason, some artists use acrylic canvas size in place of the traditional material. Utrecht Acrylic Canvas Sizing (Item 6326) can be used under acrylic dispersion primer (gesso) to achieve a tight stretch and sustained tension with acrylic priming techniques. Back to Top.

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