(My dumb ass forgot to tag)

Hello Fediverse, I have a bit of a technical question about the chemistry of resins, drying oils and their polymerisation. Related to an ink-making project of mine, I'll tell more about that later. The thing is, I am *absolutely not* a chemist, so I turn to the Internet with the hope of finding the knowledge I am lacking! I explain more in the following thread, thanks in advance for reading and feel free to answer in either French or English.

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#chemistry #ink

So, I'm a pen and paper lover, and I wanted to make a durable ink of (most importantly) open composition, preferably plant-based. Resins and drying oils have caught my interest for two reasons : the firsts have an ability to set quickly, however they remain soluble in their solvent, the others… well, *dry* (although they actually cross-link) in a longer period of time (about a week for raw flaxseed oil, can be brought to under a day). Let me get into a few details here.

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Resins, at least natural ones, are essentially made of two compounds : long, acyclic chains or carbons, and another cyclic aliphatic, with several cycles, both compounds bearing a carboxylic (R-C(O)OH) and a few alcohol (R-OH) groups. When the solvent evaporates, intermolecular forces make the resin set, and the whole thing may take years to cure, if untreated.

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Drying oils are made of unsaturated fats. The more double bonds they have, the more “drying” they are.

I am not sure what happens with the double bonds, however dioxygen from the air will create a hydroperoxyde (R-O-OH) that will allow the cross-linking of two carbon chains as an ether (R1-O-R2) and release water. Siccatives (metallic soaps) catalyse these reactions, and interestingly, they can also catalyse the polymerisation of resins (this time, through esterification).

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Now that all this is said, I believe it would be… *mechanically* beneficial to use both resin and oil, for flow at first, then for the plasticity of the dried ink film. But anyway, if I want rapid setting, I will need resin, and if I want curing, I will need the addition of siccatives. However, contrary to drying oils, resins molecules all have oxygen atoms in carboxylic and alcohol groups.

(Question coming, finally!)

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So my question is : *in solvent* (I think I'll use ethanol) and with the addition of a siccative, should the molecules of resin cross-link? And if so, can the reaction be prevented by the addition of an antioxydant (say, eugenol)?

Thanks again for your time.

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(What would be a long thread without a post scriptum?)

PS : It is going to be an artistic, small scale and artisanal process, so I do not expect to get an exact theory and there will be a lot of testing to get the recipe right, but I would like to confirm that my expectations are correct, otherwise… well, if it dries in the pot, it is not going to work!

Also, I'm a very *safety first* person, so I will be careful.

@machinart If you keep the air out and the ethanol in with a tight lid your ink will keep for some time. Linseed oil is stable in a closed bottle, but not for years.