Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: katieHaylor on 04/05/2018 11:35:18

Title: Would oxygen levels affect paintings?
Post by: katieHaylor on 04/05/2018 11:35:18
Denis asks:

Will an oxygen rich environment accelerate the polymer formation in drying oil paint?
So that paintings can be varnished and go to market in less than six months.

Conversely, would an oxygen deprived environment, say displaced with nitrogen or argon, inhibit the polymer formation of oil paint? So a longer open time for large paintings and extending the useful life of paint on the palette.


What do you think?
Title: Re: Would oxygen levels affect paintings?
Post by: alancalverd on 04/05/2018 15:28:17
Certainly worth a try, at least as far as accelerating the oxidation of fresh paint, but whilst an oxygen-depleted atmosphere will extend the working life of the paint, it will seriously reduce the working life of the painter.
Title: Re: Would oxygen levels affect paintings?
Post by: evan_au on 05/05/2018 05:18:22
Many materials used in art and literature slowly degrade over time - paper slowly reacts with oxygen in the air, and oxidises. ie the paper burns at an extremely slow rate, gradually turning the paper yellow, brown and eventually black (after centuries).

Exposure to ultraviolet light also breaks down chemicals, and this can yellow paper or break down pigments quite quickly. Varnish goes yellow, then brown, almost black. Old paintings need this degraded varnish removed to reveal the colours beneath (as was done with the Mona Lisa).

Organic dyes (as often used in oil paints) have double bonds that interact with light. UV is very effective at breaking these double bonds, so the colors fade with time. If you want long-term color, use inorganic pigments. It has been discovered that classical Greek statues and the entombed warriors of China were covered with bright color, but you have to catch the color as soon as you uncover the object, as the colour falls off and is lost as soon as you unearth it.

So if you wanted to protect your documents and artworks in the long term, keep them in the dark, in an inert atmosphere (eg nitrogen). Last year I saw some of Leonardo Da Vinci's original documents; they are rotated out of the vault for viewing for a months at a time; it is years before that page is put back on display.

See: https://en.wikipedia.org/wiki/Mona_Lisa#Conservation
Title: Re: Would oxygen levels affect paintings?
Post by: puppypower on 05/05/2018 11:48:11
Denis asks:

Will an oxygen rich environment accelerate the polymer formation in drying oil paint?
So that paintings can be varnished and go to market in less than six months.

Conversely, would an oxygen deprived environment, say displaced with nitrogen or argon, inhibit the polymer formation of oil paint? So a longer open time for large paintings and extending the useful life of paint on the palette.


What do you think?

Many paints, especially oil based paints, have undergone mandated composition changes, to meets the goals of the ever harsher clean air laws. In terms of manufacturers, most have lowered the volatile organic carbons (VOC's) by decreasing the amount of solvent and many of the traditional drying agents. These changes slow down the drying time as well as the curing process. To speedup the curing you would need to back add solvent and conditioners to make old school varnish before the sky was falling. For example, add a little naphtha; tablespoon or use some Japan drier.
 
If you don't wish to add anything, to be more clean air conscience, then use very thin coats of varnish. The thin coats will dry in a reasonable time, so the curing can begin faster. Thicker coats with the new paints often results in residual solvent stuck between coats, which impedes the curing process. This was much less of a problem with the older timer formulations.
 
Oxygen is not usually part of the curing process. The impact of oxygen is more about secondary chemical reactions; oxidation, which can change the properties of various materials and pigments. Curing is about the polymers slowly arranging in space to maximize molecular contact, which makes the material stronger.
Title: Re: Would oxygen levels affect paintings?
Post by: Bored chemist on 05/05/2018 12:02:00
For example, add a little naphtha; tablespoon or use some Japan drier.
What has the tablespoon got to do with it?
Oxygen is not usually part of the curing process.
Yes it is.
Please don't post nonsense.
If you don't wish to add anything, to be more clean air conscience, then use very thin coats of varnish.
The OP is seeking to retard drying not to speed it up, and they are not talking about varnish.

Did you actually read, and understand, the original post here?