It’s a Marathon, Not a Sprint

The past two weeks of research for me have been all about paint. Not yet the cleaning of, but rather the initial drying process that oil paint undergoes immediately after being created. Oil paint has two distinct drying phases the first being within a week or so of being laid on a surface in which a rapid change in its T2 values can be observed. This was the main focus of my work this week, making paint and then running a series of CPMG pulse sequence measurements at 20 um increment depths to create a profile of the paint and its signal decay and t2 values.

Making paint is a very hands-on process which was a welcome break from spending hours in front a computer attempting to understand MATLAB code. The oil paint I made is comprised of inorganic pigments, in this case Cadmium Yellow No. 1, and linseed oil. First the roughly desired amounts of pigment and oil are measured out, by weight a ratio of around 2:1 pigment to oil. The pigment is piled onto a glass slab then the oil is introduced using a pipette.  The two are then mixed with a small spatula then the mixture is mulled using a glass muller which is basically a very large pestle. The mixture is repeatedly mulled and gathered until the desired consistency is achieved, adding pigment or oil as necessary. Our samples were prepared on a glass microscope slide using a calibrated spreader bar which creates layers or a uniform thickness. The paint was spread in a 100 um thin layer onto the slide then was promptly placed on the PM5 magnet to proceed with the CPMG measurements.

Profiles were made for the entire paint sample in the morning and afternoon for the following two days. It was seen that theT2 of the paint decreased roughly on the order of 10 per 24 hours. To be more precise, it was decided that we would run a 48 hour experiment to get an hourly breakdown of the T2 decay. I must thank my lab mates for their willingness to help in this endeavor and take turns pushing buttons and rewriting file names for two hours at a time. I myself discovered the difficulties of day sleeping and the strange peacefulness one finds in the ISC in the wee hours of the morning as myself and one other student took night shifts so that readings could be made every hour on the hour. It was long and admittedly tedious work,  but from the early data processing worked on today, it appears the T2 decayed as expected. This knowledge of what is going on within the paint in this early drying stage will help in the understanding of the state that paint is in after it has dried, and how this state can be effected by the introduction of solvents via the cleaning process.

Once again, a huge thank you to everyone in my lab who took time away from their projects to help push buttons for mine, I really appreciate it.

Comments

  1. gladysshaw15 says:

    Making paint samples would be the last thing I would picture in a chemistry research lab! Is linseed oil the most common mix with pigments in order to make oil paints, or was this mixture only used in a certain time period?