What's a panel? To an oil or acrylic painter, it's an alternative to a canvas support. It could be of solid wood, plywood, MDF (medium density fiberboard), copper or even one of the new composites like Dibond. Sometimes canvas is secured to a panel.
A panel, like a canvas, needs a primer base and then a ground to be considered complete. Examples of primers are rabbit skin glue and acrylic dispersion primers (like Golden's GAC 100.) Examples of grounds are gesso, lead paint and acrylic dispersion grounds (like Golden's Gesso.)
Just those two little paragraphs above open to a world full of knowledge, opinions and outright nonsense. I try to wade through it all with the likes of forums within Natural Pigments and AMIEN. I keep up to date with products and research from the web sites of Golden and Gamblin. Museum sites can be tremendous sources of information for art conservation. (See here and here for starters on these stunning resources.)
I've tried linen panels but prefer a smoother surface. I'm not painting on very large supports, the biggest at this time being 16 x 24 inches. These are my surface and size requirements.
Over the past couple of years, I've tried 1/4" "Birch" plywood from the local building supplier, Home Depot. Splits in the veneer surface and localized warping plagued me.
Home Depot also offers MDF and I've been, until recently, working with their 1/8" MDF. I did find slight warping apparent in sizes over 12 inches.
I have settled on 1/4" MDF. No warping over a span of two feet.
To prepare my panels, I first cut to size on my table saw. Then over the course of a week or so, I will apply two coats of Golden GAC 100 to all sides. Then it's a coat or two of Golden's Gesso all around with a couple more layers for the front. I then let the panels sit for a week or so to dry more completely.
This little process is built upon the product information on Golden's site. It can possibly change over time so I visit regularly. My requests for technical support with Golden's products are always well answered. I like 'em!
You see, my goal here has been to establish a process that I'm comfortable working through and that I feel provides good protection for a painting's future. My standardized process feels "good enough" for me. I like that!
I do as some point want to explore MDFs. Are they all the same? Do some fit better with GAC 100? Perhaps I should scuff up the panel first?
I might want to explore grounds as well. Do I want to use a lead ground instead of acrylic? Will rolling acrylic gesso provide a smoother surface than a brush?
One could easily become lost in the technical abyss and never come out. I do have experience with that phenomenon. I think that's why my "good enough" statement is key here. I may be able to make incremental improvements in my panels but certainly don't need to delay painting. It's good enough!
(See my earlier posts on panel making here and here.)