Repost: Archival Permanence

Over time, all paint­ings dete­ri­o­rate. Badly made paint­ings dete­ri­o­rate quickly, some­times within a year or two of com­ple­tion. A paint­ing made with a high level of crafts­man­ship can last for many years before notice­able changes occur.

For most of us, it isn’t worth going to extreme lengths to make our paint­ings as per­ma­nent as they can pos­si­bly be. You could, for exam­ple, choose to paint on high-tech alu­minum hon­ey­comb pan­els. These are light, long-lasting, and much bet­ter sup­ports for paint­ing than most of those used by artists, because they don’t sig­nif­i­cantly expand or con­tract with changes in tem­per­a­ture and humid­ity. They also cost hun­dreds or thou­sands of dol­lars. If you know that you are a vision­ary artist who will be pro­duc­ing work of breath­tak­ing mag­nif­i­cence that will be of incred­i­ble his­toric sig­nif­i­cance, you owe it to future gen­er­a­tions to eat only cheap prepack­aged noo­dle dishes at each meal so that you can afford to paint on the most per­ma­nent and expen­sive sup­ports (until you work starts to sell for many thou­sands of dollars—then, go ahead and treat your­self to a nice juicy tofu burger).

For the rest of us, not so much. Most paint­ings by even fairly good artists won’t be saved for much more than a gen­er­a­tion. The best way to pre­serve your paint­ings is to make them really, really good (or really, really pop­u­lar, which 20^th cen­tury artists demon­strated to have no cor­re­la­tion with good). A paint­ing that peo­ple like a lot will be hung on a wall in a room that has a rea­son­ably con­stant tem­per­a­ture and no wild swings in humid­ity. Almost any paint­ing will sur­vive for a long time under those con­di­tions. And if peo­ple really like it, it might hang in a museum or get restored by a con­ser­va­tor if it starts to show signs of wear and tear. If a paint­ing isn’t that great, then even if it’s made with excel­lent crafts­man­ship and highly archival mate­ri­als it’s likely to be kept in the attic, base­ment, or garage for years at a time. Even well-made paint­ings won’t last long under those cir­cum­stances, and when they start to fall apart, no one will pay for a con­ser­va­tor to fix them. So the most archival qual­ity a paint­ing can have is to be so well-liked that the owner (and the owner’s heirs) could never imag­ine putting it in a moldy basement.

(Of course, if you are a very famous celebrity such as Sir Paul McCart­ney, your incred­i­bly bad van­ity paint­ings will be trea­sured and pre­served for cen­turies. Go figure.)

Nev­er­the­less, I think it’s a smart to con­struct paint­ings with qual­ity mate­ri­als and good crafts­man­ship, if only so that cus­tomers won’t com­plain until after you are dead. Here are some guide­lines for oil paint­ing. If you don’t fol­low them per­fectly, it won’t cause your paint­ing to explode. But the closer you adhere to them, the more likely your paint­ing will be to last a long time under opti­mal con­di­tions, or sur­vive brief peri­ods under poor con­di­tions. If you want a paint­ing to last a long time under poor con­di­tions, oil paint is a very bad choice of medium.

• Rigid sup­ports are bet­ter than fab­ric sup­ports. Fab­ric is flex­i­ble, and every time it flexes (as it will do when tem­per­a­ture or humid­ity changes) the bond between the sup­port and the paint is affected. Over time, that’s very bad for a paint­ing. Cop­per, steel, and alu­minum pan­els are excel­lent sup­ports for paint­ing (although they can be heavy). Wood is OK only if it has been sea­soned for a year or two after being cut and planed to size. Hard­board is prob­a­bly OK if there is a good bar­rier between the panel and the paint. Tem­pered hard­board is stronger than untem­pered and that makes it bet­ter (despite what some sources say) even though there is a slight amount of oil in the sur­face of tem­pered hard­board. Medium den­sity fiber­board is OK only if it is very well sealed on all sides against moisture.
• It may be that poly­ester will turn out to be the most archival fab­ric, because it is more dimen­sion­ally sta­ble than organic fab­rics like linen and cot­ton. We don’t know yet.
• Oil grounds are good to paint on. Lead grounds are the best oil grounds, because lead is a very flex­i­ble pig­ment. Acrylic primer (“gesso”) is prob­a­bly a decent ground to paint on (we’ll know for sure in 100 years) but mur­der on brushes. Tra­di­tional gesso is prob­a­bly an OK ground on a rigid sup­port (the hide glue in gesso is very strong, which is good, but likes to absorb water, which is bad).
• Use per­ma­nent pig­ments. Alizarin crim­son is not per­ma­nent, espe­cially in mix­tures and when applied very thinly. Imper­ma­nent pig­ments will fade or become dull over time.
• If you use linen, cot­ton, or hemp as a sup­port, don’t put paint or oil primer directly onto it. The oil will rot the fab­ric. You need a bar­rier, such as hide glue or acrylic primer, between the paint and the fab­ric. Make sure the bar­rier cov­ers the sides as well as the front of the canvas.
• Don’t apply a lot of thick paint. Thick, heavy lay­ers of impasto are much less per­ma­nent than thin lay­ers (about the thick­ness of a layer of house paint). Sev­eral thin lay­ers (allowed to dry in between) are much more per­ma­nent than one thick layer. A few expres­sive blobs of impasto here and there are not going to cause prob­lems, but large areas of thick paint are bad.
• Lin­seed forms the strongest paint film of the dry­ing oils. Wal­nut is less strong. Saf­flower and poppy are weaker still. Because the same stuff that makes the paint film strong also yel­lows, lin­seed will yel­low more than other oils. But go for a walk through a museum with paint­ings three or four hun­dred years old. You prob­a­bly don’t find your­self think­ing, “Wow! those paint­ings now suck because they’ve yel­lowed.” (Ignore Brown School paint­ings from the 17^th and 18^th cen­turies that were delib­er­ately painted with an over­all dull yel­low­ish tone.) You can barely notice the yel­low­ing, and those paint­ings were almost all done in lin­seed. Whites are a lit­tle warm, blues turn slightly green­ish. That’s how bad the yel­low­ing gets on a well-made paint­ing. It’s barely notice­able, although some paint man­u­fac­tur­ers will try to scare you into buy­ing spe­cial “non-yellowing” paints made with oils that are less strong. Per­son­ally, I only use paints made with lin­seed and, to a lesser degree, wal­nut. I avoid paints made with poppy and saf­flower. If you do use saf­flower oil, be aware that the kind you can get in a gro­cery store is almost cer­tainly not the kind that dries prop­erly when mixed with oil paint.
• There are a num­ber of good rea­sons to avoid stu­dent grade paint, but archival per­ma­nence is not one of them. Stu­dent grade paint from a good com­pany will be as archival as their artist-grade paint.
• It is best to not add any­thing to your paint—no medi­ums, no sol­vents, no noth­ing. If you do add stuff to the paint, add only a lit­tle bit (less than 20% of paint vol­ume). If you add sol­vents, don’t make the paint watery or washy, just add enough to make the paint more man­age­able. If you apply a layer of medium to the sur­face of a dried layer of paint before you paint over it, make it a very thin layer.
• It is best not to add metal­lic dri­ers to make the paint dry more quickly. If you do add them, I think that lead napthen­ate is best. Add a tiny amount (like one drop from a tooth­pick) to a penny-sized blob of paint on your palette. Add dri­ers only to the slow-drying pig­ments on your palette.
• In my opin­ion, it has not yet been demon­strated whether alkyd paint­ing medi­ums (Liquin, Galkyd, Neo-Meglip, and so on) are suf­fi­ciently per­ma­nent. They are prob­a­bly fine for sin­gle layer, direct paint­ing. I’ve heard a cou­ple of com­plaints about delam­i­na­tion in multi-layered paint­ings that may be due to use of alkyds. Some alkyd medi­ums can also yel­low quite a bit. Per­son­ally, I don’t see any rea­son to paint with any­thing that smells like that.
• If you add sol­vents and oils to your paint, and you work in lay­ers, it’s best to fol­low the fat over lean rule. That just means that no layer should have less oil in it than the layer beneath it. So be care­ful about how you use medi­ums and avoid paint­ing large areas of lean paints (with­out much oil in them) like man­ganese vio­let over large areas of fat paints (with a lot of oil in them) like ivory black. The fat over lean rule is espe­cially impor­tant if you paint in thick lay­ers. In thin lay­ers, it’s still a good idea, but less crucial.
• Var­nish the paint­ing after it is dry. By dry, I mean three months to a year after com­ple­tion, depend­ing on how thick the paint is.

Few painters (includ­ing me) work accord­ing to these guide­lines all the time, and yet their paint­ings don’t gen­er­ally fall apart rapidly. Oil paint­ing is fairly for­giv­ing, so long as you respect your mate­ri­als and stay within a rea­son­able zone of crafts­man­ship. So long as you do that, there isn’t any rea­son to worry about archival per­ma­nence unless the voices in your head are very insis­tent that you are going to be the next Michelangelo.

Per­son­ally, I doubt that the art con­ser­va­tion robots in the Lou­vre in the year 2306 will curse my name because I used sub-standard meth­ods requir­ing them to spend an extra 324.663 sec­onds fix­ing one of my paint­ings. But that would be really cool.

Update 10/23/06: One other point regard­ing how to con­struct paint­ings that will last. If you paint in mul­ti­ple lay­ers, make sure that each layer adheres to the one below it. A paint layer that is smooth and shiny is not a good sur­face for paint­ing over, because the next layer of paint has no mechan­i­cal tooth to adhere to. You may want to scuff up the sur­face with a green kitchen scrubee pad or, if you pre­fer, wet sand. If you use a medium that con­tains a bal­sam such as Venice tur­pen­tine or Canada bal­sam, the paint will adhere bet­ter to the pre­vi­ous layer.