Gamblin PVA Size is made from a pH neutral Polyvinyl Acetate Glue and distilled water. The size acts as a sealant for porous fibers of fabric or paper and isolates those fibers from your Gesso, Ground and oil colors. This protects the fibers from acid, making the surface archival.
Conservation scientists recommend painters use neutral pH PVA instead of rabbit skin glue. PVA Size provides a stable size layer that seals the canvas but does not swell or shrink like rabbit skin glue does. Over time, the repeated movement of rabbit skin size can cause an oil paint film on top to crack. This does not happen with PVA Size because the size does not re-absorb atmospheric moisture.
Only fabric and paper supports need sizing. Panel can withstand the acid in oil and may be prepared with just Gamblin Ground.
PVA Size is available in the following sizes: 8.5 fl oz, 33.8 fl oz.
A 8 fluid oz. bottle of PVA Size will cover about 10 square feet.
How to apply?
PVA Size on fabric (canvas or linen)
Use any style of brush to scrub PVA Size into your canvas. You can apply PVA Size before or after stretching. A single coat of PVA Size on the front of the canvas is usually sufficient for application. If the canvas has a very open weave showing many pinholes when held up to the light, apply PVA Size to both the front and back. If you are stretching your canvas before applying PVA Size, ensure that canvas is stretched evenly and tightly. PVA Size will tighten a stretched canvas initially when wet but may relax somewhat once dry. PVA size will not result in any dramatic difference in the tightness of the canvas like rabbit skin glue.
For very large dimension stretched canvas or when using lightweight linen, apply PVA Size first prior to stretching. Lightweight canvas on larger stretchers can buckle and/or wrinkle on the stretcher frame when dry. Heavier weight canvas has less of a tendency to buckle or loosen.
PVA Size on paper
There are papers which are already sized and designed for oil painting. Heavy water media papers like watercolor, mixed-media and some printmaking papers may be used for oil painting once properly treated. Gamblin PVA Size can be used as a sealant for that purpose. The appearance of most papers are changed very little once the PVA Size is completely dry.
Only the side of the paper to be painted on with oil colors requires sealing with PVA Size. To limit wrinkling, some papers may require taping down to a rigid panel before applying PVA Size. Allow the sized paper to dry completely before removing the tape. Most paper will require 2 coats of PVA Size. Allow all moisture to evaporate out of freshly sized paper (about 24 hours) before applying Oil Ground and/or Artists Oil Colors.
PVA Size alone - with no additional primer?
Can I use PVA Size on its’ own as the primer, without an additional gesso or ground?
Yes! PVA Size can be used on its own as your ground without the use of a white or colored primer over the size. This can be used when a painter wants to allow the natural color and look of the canvas or paper to show through in parts of their oil painting. Although PVA Size is not itself a ground, it may be used in lieu of a white covering primer to protect canvas from the acidity of oil colors.
In these scenarios you should apply two applications of PVA Size to help reduce the absorbency of your canvas. PVA Size is formulated to go on very thinly without filling in the natural texture of the canvas.
Cleanup?
This product is water soluble. Soap and water can be used to clean brushes after application of PVA Size.
If allowed to dry in bristles or on unintended surfaces, PVA Size can be removable. Dry PVA Size can be cleaned off hard surfaces with bar keepers friend.
