I just acquired a 10' x 1' porcelain Standard Oil Company sign that was buried in dirt for the last 30-40 years. There is minimal rust, but a lot of "crud" from being buried for so long. I have been washing with soap and water, but some of it is really stuck on. I currently have it covered with damp towels to try to soften the crud.
I thought about using my power washer, but don't want to mess it up.
Any ideas would be appreciated.
Welcome to Oldgas. Here is a thread regarding the cleaning of porcelain signs. You might try the search button for more assistance. Good luck!
http://www.oldgas.com/forum/ubbthreads.php?ubb=showflat&Number=739443&page=1
Take some pictures along the way and see if there are stains on the back side that will provide a preliminary test site for what ever you decide. I have had luck with stripper on paint and oven cleaner on stains IF the sign is porcelain.
I used a google search after I asked and found several threads on here. Barkeepers Friend and a scotch brite pad are doing a good job.
Please post a picture of the sign if you can.
Rob
Zud is really good on porcelain.
How about a little bit of Comet cleanser, water from a spray bottle, and a fine grade 3M pad.
After cleaning my sign I think elbow grease is the most successful.