I have to begin tonight with a correction. I mistakenly said that linseed oil used as a food was called rapeseed oil. Rapeseed oil is canola oil. I was wrong and several readers set me straight in my e-mail. My apologies.
I was asked in the comments about the permanence of alkyds and acrylics.
- Alkyds are made by treating drying oils, such as linseed or soybean with an acid. There are two ways of introducing alkyd into your painting. The first and most common is the use of an alkyd medium. Liquin and Galkyd are the best known alkyd mediums. I use Liquin . Graham also makes a walnut oil based alkyd. The Graham is the most glossy followed by the Galkyd with the Liquin having a more satin finish. They give a faster drying time and help prevent drying in. That is when the darks in a painting lose their gloss and look matte compared to other parts of the picture.The second means of introducing alkyd into a painting is the use alkyd paints. There are now several on the market. The only one I have used is Griffin alkyd made by Winsor Newton. I have used their alkyd white for periods of time and added a few colors of theirs to my ordinary palette. Regular oil paint and alkyds are compatible and can be used together. Alkyd makes a tougher paint film that ordinary oil and it has a flexible :"rubberyness" that is very durable. It lacks some of the "jewel like" look of oil paint. Some people find the vapors from the evaporating alkyd mediums irritating to their sinuses.
- Acrylics, formerly called polymer colors, are a plastic based paint that has become very common with "modern" artists and are less commonly used by traditional painters. The drawback of these paints is their rapid drying time. While that might seem an advantage, the longer open time of oils allows greater manipulation of the paint, such as blending, before it dries. I don't like working with them. They have been around since the late sixties and while they seem to be permanent, I suspect they are probably less so than oils.They are still well within the boundaries of archival and if you like using them I wouldn't worry about that. They look a a little different than oil on canvas and I feel they have a slightly plasticy look to them. They often seem to lack the glow of an oil painting. There are many brands of acrylic that are more student grade than professional. They are often marketed to students and amateurs. Almost none of the paintings in the galleries I show in are acrylic. I think the buyers prefer to hear oil rather than acrylic. In the "modern" art world this seems to be reversed and there are more acrylic paintings. Acrylics do not require noxious solvents though, and that is the major reason for their popularity I think.