Cleaning Portable Rock Art

Most portable rock art are surface finds. I've written an article on cleaning portable rock art with caveats and considerations.
https://www.rockartmuseum.com/cleaning-rock-art/

To Clean or Not to Clean by Virginia Steen-McIntyre, PhD
“This is not as important with surface finds, they can be any age, but it becomes critical for an artifact dug from an intact sediment layer. That sediment layer (perhaps at the time only ‘dirt’ to you) may harbor clues to the age of your piece in the form of organic matter for 14C dating.”

Example of how cleaning (carefully) can bring back the original visuals

Its also important to be careful not to scrub off any pigments, although the black pigment on my own finds is very resistant......

This is an example of "tar" applied to carved wood with many effigies. It is obviously not portable rock art but it demonstrates the importance of not removing organic material which can be dated. I found it after massive flooding a couple years ago. Who knows how deep it was buried and how much "tar" was initially applied.

It does seem to have some of the standard topology in there....

U no, I have been wondering about some of mine that look as if they need to be cleaned. Wondering if they purposely put or left "stuff" on there. Then created thier art on the rock s using a medium.

Soil and organic material naturally binds to rocks over time. How much encrustation depends on how long its been since it was carved. It also depends on surrounding mineral types, climate, its final resting place such as on the surface, buried or in water etc etc.. Dating portable rock art is extremely difficult https://www.rockartmuseum.com/dating-portable-rock-art/