Ever since I started oil painting, I get a lot info on how bad the solvent is, especially its vapor (fume). Someone even describe it as an evil.

Well, as a formal chemist, I need more data to prove any statement rather than description or imagination only. So I download the MSDS file and I calculated it based on my working condition.

Take Gamsol as an example.

In MSDS document, you can find several tables like these,

Now, I’m going to start with how I use the solvent for oil painting. Usually I’ll put premixed solvent in a droplet bottle and use drops when I need it. In this way I can keep the solvent as less as possible. I don’t want to use a wide mouth jar and find myself forget to close the lid.

Assume I use pure mineral spirit only.

1 mL = 20 to 22 drops of liquid

I only use less than 5 drops each time, therefore,

5 drops = 0.25 mL = 0.25 (cm^3)

Density = 764 kg/m^3, therefore,

Mass = 0.764 g/cm^3 × 0.25 cm^3 = 0.191 g = 191 mg

My active working space is small, about 8 ft by 8 ft by 8 ft,

1 ft = 0.3084 m

8^3 (ft^3) = 2.43^3 (m^3) = 14.35 (m^3)

Therefore, the concentration of solvent in my working space is,

191 mg / 14.35 m^3 = 13.31 mg/m^3

Compare to the vapor limit in MSDS which is 1200 mg/m^3, this is not a significant amount. And this is under pure solvent condition, if I mixed the solvent with linseed oil, the number would go down based on mixing ratio. According to Dalton’s law of partial pressure, when I mix solvent and oil at 1:1 ratio, the concentration of solvent in my working area would be cut in half, that is 6.65 mg/m^3. Furthermore, if I have larger working area, this number would even go down. And don’t forget the ventilation. I always has the ventilation fan on, this would help to lower the concentration of solvent evermore.

Another factor is the density of solvent vapor. According to MSDS, vapor density is 5.6 at regular air pressure where air density is 1. This means the vapor of solvent is heavier than air and would go down towards the floor. Unless you stick your nose on the solvent jar or put you nose below your painting palette, you are highly unlikely to breath in the vapor.

Last but not least, the exposure time. The animal toxic results are based on long time (8 hours) exposure to high concentration (>5000 mg/m^3). Assume you can reach that high concentration of solvent in your working area, you have to work 8 hours straight to get minimal toxic effect. In fact, I usually take a break every 2 to 2.5 hours.

In summary, working with oil painting solvent such as Gamsol is safer than you thought, as long as you work in a manageable way. I didn’t check other solvent such as terpene. But whatever you use, please refer to MSDS file first and you can find out if that is safe for your tolerance.

Again, this is just a simple calculation I did to help me understand “how bad the solvent is”. If there is anything wrong with the calculation please feel free to let me know. I hope this would help you a little bit.

Don’t be scared or terrified by the oil painting solvent.

Thank you very much~