I have experimented decorating paper for lamp shades, and to oil them making the paper more transparent and vibrant in the colours.
I have mostly tried linseed oil as a) it is harmless (you can eat it) and b) it has a long tradition in painting furniture, houses etc. I have seen someone use argan oil, and there is a huge number of other oils available. Question: Have you tried to oil paper? With what experiences on a series of parameters: Applied before or after folding? Ease of application? With what kind of oil? Effect of transparency? Discolouration when applied? Yellowing over time? Effect on colours? Curing time? Greasiness? Folding properties? Smell? Toxic? Other remarks? As to my experience with linseed oil: When applied? I have mostly applied it before folding, for several reasons: The paper becomes stronger. It is easier to apply oil to both sides of the paper before folding. Easier to wipe off excess paper. Ease if application? Easy, using a rag or some tissue paper. Those may self-combust. Always put the rags out flat to dry, or store in a closed container, never just throw them in the litter. No airing needed while working with the linseed oil. Transparency? The paper becomes nicely transparent. I don't have a comparison scale, though. Discolouration, and yellowing over time? Natural linseed oil is slightly yellowish, and becomes more so over time. This can be alleviated by using linseed oil bleached by activated carbon. Effect on colours? Using the bleached quality, the colours are preserved, but becomes more transparent and vibrant. Curing time? Well, long. Be sure to wipe all excess oil off, otherwise the curing takes even longer. Greasiness? Slightly oily even if wiped off carefully, until cured. Folding properties? Excellent. Thin paper becomes easier to handle, and thick paper doen't break as easily. Smell? It has a slight smell of, well, linseed oil until completely cured. Toxic? Linseed oil is edible. So good. Other remarks? A downside is that unless the oil is thoroughly hardened, glue or tape adhere badly to the paper (and yes, you use that, or sew, when assembling lamp shades). I guess many of these properties are shared with other oils, but to varying degrees. As I have no comparative scale, and little chemical insight, the observations are pretty subjective, but hopefully still somewhat useful. Best regards, Hans Hans Dybkjær http://papirfoldning.dk Society: http://foldning.dk