FAQ – Technical Q’s Compilation
After many years of writing these technical Q&A articles, as well as doing countless presentations and workshops on ‘the craft of painting’, I thought it would be a good idea to review the most frequently asked questions (FAQ). My goal has always been to help people become better painters, more skilled and knowledgeable about how to use the tools of the artist’s craft to create art that will last for generations.
Q: What is the best support for paintings?
A: Overall, untempered hardboard is the most permanent and economical support for oils, acrylics, and mixed media. Acrylics will remain flexible indefinitely so just about any surface they will adhere to that is permanent is OK. They are sensitive to acidic elements so sizing a support made of wood for example, is important. Oils become more hard and brittle with age so prefer a non flexible support like hardboard. Unlike acrylics, oil paints are acidic so supports like canvas need to be protected from coming into contact with them. You can prepare canvas to be more stable and less flexible for oil painting. Refer to my "Oils on Canvas" blog post for instructions on how to prepare canvas for oil painting.
Q: Is commercial primer or house paint from the hardware store suitable as a ground instead of gesso?
A: These products are not made for permanent painting applications. They would be OK to use for beginners and practicing.
Q: Can I use gesso to cover an old painting before painting over it?
A: Not if you want it to last, esp if it is an oil painting. If you are not concerned about permanence then you can paint over it with white paint, not gesso, and start a new painting. Gesso will not stick to paint, it is a ground (primer), and has very little adhesive strength.
Q: Can I paint oils over acrylics?
A: Yes, oils will stick well to acrylics, but not vise versa. I would suggest this practice be done on a rigid support (see above).
Q: Is it OK to dilute my oil paints with solvent and my acrylics with water?
A: Oils and acrylics are ‘body’ paints so unlike water media paints they are designed to be used thick and rich in texture. Diluting them with solvent (oils) and water (acrylics), more than about 20%, will make the colors dull and the paint film weak and unstable.
Q: Is a mixture of linseed oil and solvent a good medium to mix with oil paints?
A: No, good quality oil paints already the right amount of oil in them. Oil tends to yellow and wrinkle with age, adding more oil compounds this problem. Use a small amount of good quality alkyd resin medium instead to mix with your paint.
Q: Can you explain the ‘Fat Over Lean’ principle in oil painting?
A: Briefly, it recommends that you not paint a fast drying color over a slow dryer. Also, a color with high oil content (fat) should be painted over a pigment with low oil content (lean) for better adhesion, and not the other way around.
Q: Is it safe to mix different brands of paint?
A: Yes, as long as they are of the same quality. Mixing low grade inexpensive paint with good quality professional colors will yield unstable results.
Q: Is there a technical reason to not use black paint?
A: No. It is interesting to note however that for hundreds of years great painters avoided mixing colors until the advent of the color wheel and the theories that have been built up around it. Any mixture of two or more colors will always be duller and less vibrant than a single pigment color, including black.
Q: Why are some brushes so expensive? Is it important to use good brushes”
A: There is no technical reason to spend extra money on good brushes but from an artistic point of view good quality brushes will give you much more flexibility and control in oils and water media paints. This is not the case with acrylics because of the nature of the paint and so cheap brushes tend to work fairly well.
Q: Can all the different acrylic mediums be mixed together?
A: Yes, with one reservation; it is not a good idea to use an abundance of hard mediums like molding paste and pumice gel on flexible supports as they are more likely to crack.
Q: Are oil paints more toxic than acrylics or watercolor paints?
A: No, they are all equally toxic. The pigment (color) is the toxic ingredient, not the binder/medium. Treat them all with care. Some people are sensitive the the volatile solvents given off by oil paints.
Q: Acrylic paints are relatively new, are they permanent?
A: Yes, they are very durable and stable and accelerated aging tests show that they will last for centuries under normal conditions.
Q: Should paintings be varnished?
A: It is a good idea to varnish your oil and acrylic paintings so that they can be cleaned without damaging the painted surface. The best picture varnishes are acrylic solution varnishes. Acrylic paintings need two layers of varnish: an 'isolation' coat, then the final picture varnish. Wait at least 3 months, depending on the thickness of the paint, before varnishing oil paintings.