Personally, I prefer painting on a hard surface so I am addressing how to prepare a panel for painting.
I will discuss hardboard, MDF, particle board, plywood and cardboard, and I am only discussing rigid panels right now, we can discuss canvas, papers etc some other time.
First I will discuss the materials, then their preparation:
For smaller work I prefer “Masonite” [ironically the Masonite company no longer makes “masonite” hardboard] which is a high density hardboard and is made by steam exploding wood into very fine fibers then re-compressing those fibers under very high pressure and heat so that the natural lignin re-bonds the fibers. the problem is that the lignin is acidic and is the material that causes cheap paper like newsprint to turn yellow overnight. There are many grades of these hardboard products, ignore the cheaper ones, currently the better grade in 3mm [1/8 inch] thickness, canvas back, is 11 dollars a 4 x 8 sheet at Home Depot. The 3mm is ok for smaller stuff, the 4 or 5 mm is better for medium sizes but as soon as you get over 16 x 20 this material starts getting pretty heavy.
The Apersan panels are “masonite’ type hardboard with frames made from birch plywood, these are very nice panels!
The ideal hardboard panel is pre-coated with Melamie on both sides and is used in the furniture industry, but it is hard to find.
MDF is medium density fiberboard and is widely available, cheap, and very flat, it is made also by steam exploding wood into fibers but the difference between MDF and masonite is that it is not compressed as much and plastic resins are added as a binder then it is put under heat and pressure. It is widely used in furniture and cabinets. It is not as strong as “masonite” so you are need a thicker panel to start with and thus the end result will be heavier, the other problems are low moisture resistance and the edges are easily damaged. Maya Lin uses MDF in her room sized contoured sculptures, it is actually a very attractive material in its self.
Particle Board, this is often confused with MDF, it is sawdust [not separated fibers] bonded with resins and is very easily damaged and has very little moisture resistance, plus it is heavy, but it is cheap. I see no reason to use this for permanent work and not many reasons to use it at all. It is used in the lowest grade of cabinets.
Cardboard, There are many grades of paperboard, for painting you should find an acid free board, forget anything like poster board which is re-cycled newspaper or other cheap board because it will become brittle very quickly. There used to be materials called Millboard and Upson Board, these were recycled newsprint bases with a top layer of a better grade of paper with a glue sizing. I doubt if these are still made but if they are I don’t recommend them. Corrugated cardboard is light but the flutes will telescope through as you paint unless you are attracted to it’s funky qualities, it is not a good painting support.
If you are using a cardboard, you must gesso both sides, otherwise it will warp badly. Painting on un-prepared board is certainly possible, but be aware that oil paints will degrade paper in a few years and make it brittle, also the paper will soak up the oil and make the paints dull. If you use acrylic paints you avoid the oil to paper degradation issues but be aware that the absorbancy of paper will sometimes dull acrylics. For studies I sometimes use Canvaset paper which is paper with a canvas texture and a glue or gelatin sizing. This is ok but the sizing is a bit to slick in my opinion. If your looking for a cheap support and no prep work then this is probably the cheapest option.
If you are going to properly prepare cardboard it is just as much work as better materials with little difference in the costs of the actual materials, so why bother?
Plywood: My preference second to “masonite” for small work and my first preference for larger work is plywood. Plywood is made of thin veneers of wood, coated with glue, laid perpendicular to each other and pressed together under very high heat and pressure. Various grades have differing levels of strength, stiffness, moisture resistance and warp resistance. I have painted on Luan, Birch and Fir and prefer Luan. For smaller panels 6mm [1/4″] is ok, for larger panels that need a structural frame, I use 3mm [1/8″]. You can make a high quality, light weight, stiff and flat panel in quite large sizes with a bit of work. Top grade fir plywood is very expensive now days, the ordinary stuff would not make a good support since it easily warps, has voids, the texture will telescope when primed, etc etc.
For smaller work, up to 12 x 16 inches or so, that is going to get a decorative frame, you can use 6mm [1/4″] luan without a structural frame, over that size you are going to need a structural frame so you may as well use the thinner and lighter 3mm.
Luan plywood varies widely in quality, I find that the luan panels carried by big box lumber retailers, like Home Depot, are lower quality than what the independents carry. Look around for a wood panel dealer that sells to cabinet makers, they will have better quality materials for about the same or lower price. I recently bought some top quality 3mm luan panels for $8.40 a 4 x 8 sheet.
For making frames for larger panels, I use poplar or top quality pine. Again finding a independent wood dealer that has better quality materials will pay off here. Poplar is available in the big box stores like Home Depot, it is clear and straight and just a bit more than their terrible “select” grade [which 30 years ago would of been used for furring strips]. Which ever wood you use hand select each piece for straightness.
Rip the lumber into 3/4 x 3/4 or 1 inch wide strips, do your best to cut out defects.
To frame a panel, start with a smooth flat table top. Lay your cut to size luan face down [best way to cut luan is with a utility knife and a new blade] Then use wood glue and clamps to glue a perimeter frame onto the edge of the luan. I do two sides at a time, using a 36 x 80 inch flush door as a table top, the luan and frame gets clamped to the door so to keep it flat, once the glue sets up, rotate the panel and do the other two sides. Once all 4 sides are set up you can add bracing across the panel. The larger the panel the more bracing needed. I use smaller strips to save weight, 1/2 x 3/4 or so work, these get glued to be back of the panel between the frames. [photos to follow].
I had a panel that I unwisely used lower grade pine to frame and it warped badly. To salvage it, I glued a second 3mm sheet of luan on the back side creating a hollow core panel, just like a hollow core door. BTW, hollow core doors make a good painting support, but are relatively heavy.
Let the glue set up over night with the panel laying down flat. Then sand any rough edges and you are ready for the next steps.
Panel Priming: Priming has to do several things, it has to isolate acids that may exist in the support materials, protect against moisture, stabilize the support, and to provide a receptive painting surface.
When preparing “masonite, plywood, mdf, or cardboard, I find that a sealer coat of shellac is ideal, Shellac does not raise the grain or cause warping and it does not react with gessos. Shellac is available in paint stores as clear [traditionally called white], orange [clear amber] and as a white pigmented primer or BIN. [Note that BIN sells primers with similar labels, make sure you get “shellac based”]. I use white pigmented BIN, some painters like painting directly on clear shellac on luan.
For unsupported panels, first sand the panel using an electric vibrating sander and 80 to 100 grit sandpaper. You want to “break the glaze”. Then coat both sides and all edges of the panel with shellac. A disposable brush works or a small roller is even better. A single thin even coat is all that is needed. Let dry. Coating only one side may cause the panel to warp, if not right away then later at the worst possible time.
After the shellac is dry, go back with your vibrating sander and give it a good sanding, knocking down raised grain, splinters, rough edges, etc. 100 grit open coat sand paper is perfect for this. If you don’t already have a sander I can recommend the 1/4 sheet sanders, I have had a Porter Cable for 8 or 10 years and I use it constantly.
After sanding, you are ready to apply the gesso. I use acrylic gesso, others prefer oil ground, or other traditional grounds. Discussion of grounds is involved and will be the subject of another artical.
You can brush or roll the gesso on. I use 1 inch diameter foam rollers which leave a nice even light texture. Between uses I don’t wash them but keep them in a zip lock bag. I now just scoop gesso with a spoon from the gallon pail onto the horizontal panel or canvas then roll or brush it out. Doing this eliminates the waste you have with a roller pan and saves some clean up.
The first coat should be thinned out so to flow into any textures. Following coats can be to your taste. Different brands vary widely in handling characteristics. I find that the more expensive brands thinned down work better than the cheaper brands which start out thinner. At least 2 coats are needed, I put on 3 or 4 until the coverage is uniform. If you prefer a non-white ground, you can add some acrylic color to the gesso. I paint in oil and prefer to apply a thin oil color wash over the acrylic gesso when I start painting. I think the oil is more receptive to the subsequent layers of oil paint.
After the gesso is bone dry, sand it again. You should experiment here. It is possible to get too smooth and slick of a surface that will give your paint a smeary effect, too rough of a surface can interfer with details, for instance, but this is a matter of your taste and intent. I find that the foam rollers leave a nice pebbly surface that is just right after a quick sanding with 120 grit.
I highly recommend that every artist own a copy of Ralph Mayer’s “The Artist’s Handbook of Materials and Techniques”. First written in 1940 and revised many times since, it has a breath and depth not matched by any other reference. Every artist should read it cover to cover, not only to learn about their own media but to understand what artists working in other media do, also what is possible and what may be detrimental to your intent. It also helps you to understand how and why historic works were done they way they were. THis book should be part of any artists education in my opinion. I often see these in used book shops and garage sales [sometimes unread] and I always grab them and pass them on to worthy recipents.