One of the common concerns that wetplate collodion photographers have is how long will their plates last, with various varnishes. Most prefer a varnish that is very long lasting, or archival quality. In 2009 I started an experiment as to the archival quality of Sandarac varnish, that is still ongoing, as of 2020.

Many modern, synthetic materials have been tried, that seem to work well in the short term. Acrylic Polymers such as made by Liquitex are often used. What we know is that in the past, when ambrotypes and tintypes were a new process, photographers used natural varnishes. These are made from materials such as Sandarac, Shellac, or other hard lacquers dissolved in a solvent. These original plates often have survived 150 years and are in excellent condition. Most are stored in Union Cases, or framed though.

My question was how long will Sandarac varnish last in a moderately harsh outdoor environment? I did not compare it to another plate with Liquitex, unfortunately.

The formula was out of Coffer's Doer's Guide, and consists of Sandarac crystals, Everclear ethanol alcohol, and Lavender Oil.

I shot this plate and varnished it in 2009. Somewhere on this forum I think I have it posted. Also here. This is how the plate looked in 2009, freshly varnished:



I affixed the plate to my front door. There is an overhang, and little direct sun hits the plate, except in the morning, at an acute oblique angle. It hasn't been touched other than moved slightly a few times, in 11 years. The temperature fluctuates between the high 20s in the winter to 107 degrees in the summer. There are frequent rain and dust storms that blast the area. For all intents and purposes, there is no damage or fading of the plate or varnish.