TIPS FOR OIL PAINTERS 
WHEN CAN I VARNISH ... A short answer is "when it is dry," but that can vary by a factor of 50 or more. If you have painted thinly and used a fast-drying medium, you may be able to varnish in as little as two weeks. Thick layers containing slower-drying colors may take two years or even more. Since both extremes vary from the oft-repeated six months to a year, we hasten to add that the answer comes from Robert Gamblin, America's leading authority on oils, not us. For more information check Gamblin's website. It's listed on our links page.
THE ODORLESS TURPENTINE MYTH ... Every year we get dozens of requests for it, but like unicorns and dragons, there ain't no such animal. Genuine artist grade turpentine is still available, but all forms are odorless only when compared to mustard gas or ammonia. The odorless substitutes on the market are petroleum distillates, i.e. mineral spirits, regardless of what catchy name they may employ, and we see no reason for you to spend extra money because they imply otherwise. We should warn you, however, that lack of odor, like beauty, is in the eye (or nose) of the beholder. Some odorless thinners truly do have no smell; others are less forthright in their odorless claims. (We've done the sniff test so you don't have to.)
YOU CAN'T PUT THE OIL BACK IN THE TUBE, BUT ...
If you squeezed too much out, move the excess onto a sheet of glass or a metal palette and submerge it in water. It won't last forever, but most colors will remain usable for several days. (Need we add that this advice does not apply to the new water-soluble oils?)
MINERAL SPIRITS VS. TURPENTINE ... Although some artists remain committed to turpentine as a solvent for oil paint, mineral spirits is not significantly inferior for most applications, and has the advantage of lower cost. One major exception is in mixtures containing damar varnish. Turpentine should be preferred in these because damar is only partially soluble in spirits.
AND SPEAKING OF SOLVENTS ... You can reuse most of the mineral spirits in which brushes have been cleaned. Start by letting them stand in a clean jar overnight (longer if you wish). Pour the partially cleared spirits into a second clean jar, passing it through a coffee filter, and taking care not to disturb the residue at the bottom. Repeat if necessary, but it probably won't be.
MY OILS WON'T DRY! ... Several times a year we get that plaintive cry from a neophyte oil painter who thinks something is wrong with his paints. In fact, different colors dry at different rates because their pigments react differently with the oil itself. The range for dry-to-the-touch between fastest and slowest is about 2-12 days, and paintings of average thickness will not be fully dry for three to six months. (An older standard suggested waiting a full year before applying a final varnish, but Ralph Mayer's monumental work, The Artist's Handbook of Materials and Techniques, suggests that this was more appropriate when extremely thick, mastic varnishes were in use. Mayer not only accepts the shorter period, but maintains that especially thin paint coatings or glazes may be varnished as soon as they are dry to the touch.
OILS DRY TOO SLOWLY, BUT I HATE ACRYLICS ... If that's your plaintive cry, there are alternatives. Griffin Alkyds from Winsor & Newton are chemically modified oils that remain workable for hours, but dry overnight (and final varnishing can be done in four to six weeks). Another option is Leonardo Oils from DaVinci. They are an oil-alkyd blend and also dry faster than conventional oils. Both products are compatible with your regular oil paints. (If you mix them, follow the fat-over-lean rule.)
PINHOLES OR GESSO, IT'S YOUR CHOICE ... If you paint in oils and aren't concerned about permanence you can skip this paragraph, but if you hope that your next painting will someday hang in a museum (or even on your great-granddaughter's wall), pull out as magnifying glass and take a close look at a factory-primed canvas. What you'll find are pinholes in the coating, and each one is a potential pathway for oil, which is acidic, to migrate to the unprotected canvas itself, eventually destroying the affected areas. If you want permanence, you need to gesso the surface before you lay down the first brush stroke. Acrylic painters can ignore this warning since their medium of choice is not acidic, but for oil painters it's pinholes or gesso, with no real middle ground.
A BRUSH-CLEANING ALTERNATIVE TO MINERAL SPIRITS ... Oil painters thinking of switching mediums because of an acquired allergic reaction to mineral spirits might want to try substituting linseed oil as a cleaner. It works about as well, and is probably easier on brushes to boot. There are also citrus-based cleaners available.
TIRED OF THE SAME OLD SURFACE? ... What about trying oils on watercolor paper? Gesso it first, then treat it just like canvas. Pick a paper with deckle edging if you want to "float" it in a frame.
TIPS FOR ACRYLIC PAINTERSTO SLOW ACRYLIC'S DRYING TIME ... Overly fast dry is the curse of all acrylic painters. To gain some measure of control, try one or more of the following: (1) Add a retarder to your paint. It's glycol-based and comes in either jars or tubes. The gelled tube form will give you more open time. Don't overdo it. The maximum should be about one part to six in earth colors, and one part to three in other colors. (2) Spray a fine mist of water over your palette from time to time. A simple pump mister will do the job. (3) Invest in one of the many palette boxes that come complete with special palette paper and moistening sponge, and keep the lid on as much as possible. Between sessions store it in the refrigerator if there's room. You'll be surprised how long your paint will remain workable.
VARNISHING ACRYLIC PAINTINGS ... There's a common misconception that acrylic paintings don't need varnishing. Here (thanks to a Liquitex technical bulletin) are some reasons that's not so:
Acrylic films are porous. Without varnishing they can absorb grime from the atmosphere.Varnishing boosts brightness and color saturation.It can adjust otherwise uneven surface sheen.It allows easy cleaning without the danger of removing the paint film.It helps protect colors from ultraviolet light.For a deeper discussion of varnishing acrylics ask us for a copy of the bulletin, or go to http://www.liquitex.com
GENERAL INFORMATIONSIGNATURE ARTISTS AND PRICES ... We're not refering to painters who sign their work. Signature artists are the television painters who use their shows to promote brushes, paints, etc. bearing their name. Almost invariably these products are priced far higher than identical (or nearly identical) products from other manufacturers. It's clearly your perogative to pay extra for a TV artist's name on the package if you choose, but if you would rather save money, ask us if there isn't a lower cost substitute. Often there will be.
LENGTH MAKES STRENGTH ... One reason linen canvas is considered superior to cotton is greater strength, the result of linen's fiber length. In Belgian linen, the best grade, fibers can be as long as 26" and are less than 10" only rarely. (Cotton fibers are only 1" to 1-1/2" long.) It's for this reason that linen as much as 9,000 years old has survived to our time.
IS THAT TUBE OF PAINT REALLY EXPENSIVE? ... It may cost a lot less than you think. Superior paints usually have vastly higher pigment loads than lesser varieties, thus it will take much less paint to achieve a particular tint with a better paint than with its cheaper cousin. If you do need to economize, consider using student grade paints in the earth colors (where fewer quality-differences exist) but buy artist grade for the more intense, vivid colors.
BLACK AND YELLOW DO MAKE GREEN ... While it may sometimes be useful to know the headlined statement, if you simply want to reduce the brilliance of a pale yellow, try mixing in a bit of brown. You'll avoid the greenish cast that black will give it.
SOMETIMES BLUE AND YELLOW DON'T MAKE GREEN ... Early exponents of pointillism discovered that sometimes when the brain interprets colors the the results conflict with theoretical expectations. Alternating dots of blue and yellow tend to merge into a grayish mass when viewed at a distance. Add in lots of (pre-mixed) green dots and the blues and yellows will behave.
YOU SAY THALO, I SAY PHTHALO ... We're asked about this so often that we had to throw in an explanation. About when phthalocyanine colors were being introduced into paints, one manufacturer (Grumbacher) obtained a copyright on the simplified version, thus compelling other manufacturers to adopt the lengthier but more erudite spelling and confusing a generation of artists. Be assured that however you spell it, it's the same thing.
FOR FANTASTIC SPECIAL EFFECTS ... Introduce yourself to Pearl-Ex dry pigments. They come in a multitude of metallic shades, plus duo-color and irridescent colors. Sprinkle or dust them on or add them to any medium. They are great for replicating the shimmering appearance of silks or satins.