Cleaning Pottery

By Chiquita Prestwood

The following is content from a presentation I made at this year’s banquet and we are including it in this Journal Issue as requested by several attendees for future reference. Many times through the years I’ve been asked how I clean my pottery. I use Dawn Dish detergent for gentle washing. I have used paint remover on pieces that have been painted a different color. I’ve even been known to take a Brillo soap pad to stubborn spots.

To get a better idea of what others use successfully I asked a few McCoy and Pottery collectors to share their cleaning tips. I came up with various good suggestions from those I asked “How do you clean hard to clean pottery?”

Dewayne Imsand said he has used vinegar on a scrubber sponge with great success.

Craig Nissen has also used paint stripper for removing paint from McCoy. Lime-A-Way is a product he’s used for removing heavy calcium buildup in large jardinières. Craig’s directions are to apply Lime – A- Way. Leave it on, then scrub & wash it off….more on and soak ….scrub & wash until you’re satisfied with the result.

John Vorisek replied that he uses Soft Scrub in the squeeze bottle. “I soak the piece in water overnight and then, with rubber gloves, apply a 1/4 inch or so coating of Soft Scrub. I let it set there for at least a day or two, then use a scrub brush on it the next day, keeping the Soft Scrub at full strength. If I think it needs it I might even apply more Soft Scrub and let it soak for another day, with more scrubbing to follow”.

Ron Schuller: “For general dirt and grime and maybe light lime deposits, I use automatic dishwater soap such as Cascade. I apply the soap and then add hot-warm water and let soak overnight. For crazing, you can soak in vinegar for several days to a week, then resoak in plain water the same number of days. For really nasty stuff use lime away or even toilet bowl cleaner. The lime away is probably safer for lime deposits but the toilet bowl cleaner will do it.”

From Wes Brauch: “20% peroxide for 3 days, rinse, dry bake for 15 min at 180 degrees, repeat until clean.

Our favorite McCoy auctioneer, Jeff Koehler, recommends 409. “Often it pulls dirt from tight hairlines and crazing. D&L hand cleaner works well, too. I have also submerged pottery into an apple cider vinegar solution and put in the oven on a low heat for several hours. It will sometimes pull stains out of stained pottery.”

From other friends who collect and deal in pottery: “For the insides, I have used denture cleaner. On the outside and inside of pottery I’ve also used the Mr. Clean White Sponge.”

From a North Carolina Collector: “Soak in peroxide from a beauty supply store. It is the strength they use for perms. Soak as long as it takes. I’ve left pottery in peroxide for a month. Sometimes if a piece will not come clean, I will put it in the oven at 200 degrees for 1 hour. Turn oven off and let cool down before opening the door as temperature change can cause pottery to crack. Repeat if necessary. You would be amazed at what the heat will bring out of pottery.” If your pottery has hand decoration, be very gentle with it. Just barely blot the item with a moist paper towel to preserve the paint. I would not recommend using any of the above cleaners; at most a dab of dish detergent on your moist paper towel.

Some Miscellaneous Posts on Cleaning Pottery

Cleaning dirt and grime from pottery: Soak for at least 24 hours in hot water and ammonia mixture. Typically a cup of ammonia per 2 gallons of water. Some have reported additional success by adding Spic and Span to the ammonia/water mixture. Removing silver or pencil marks from pottery: The best thing to remove silver or pencil marks from matte glazed pottery is metal polish. Some have found Noxon to consistently be the most

effective. Simply put a little polish on a rag and rub the silver marks. After silver marks are removed, use a clean part of the rag and buff remaining polish off.

Removing mineral deposits from pottery: To remove mineral deposits such as calcium, lime, and rust stains, soak the piece in full strength white vinegar. For lighter mineral deposit staining, a day or two of soaking in the vinegar should do it. On pottery that has extensive mineral deposits, extended soaking may be required. On pottery requiring extended soaking to remove lime or calcium buildup, rub the problem deposits daily with a butter knife to break up the deposits and allow the vinegar to better penetrate the buildup. For extended soaking, change the vinegar regularly. After you have the pottery as clean as you can, wash the vase with soap and warm water. Then soak in tap water until vinegar smell is gone.

Removing darkened crazing from pottery: Hydrogen peroxide can be used to lighten darkened crazing. Use only 40% hydrogen peroxide and do not dilute. The lightening process will not be successful if you use a lesser strength solution. Be sure to use waterproof gloves and protect exposed skin. Soak pottery in the peroxide solution for weeks if needed. Over time the peroxide loses its strength if exposed to the air. Use a sealed container and change the mixture occasionally. Periodically check pottery to see if crazing lightened. If not, continue soaking.

Removing paint specks from antique art pottery: Acetone is very effective at removing paint specs. For thicker and aged paint specs, you may need to use a safety pin or needle to scuff or flake the paint to allow the acetone to work into the paint.

One person used Oxi Clean on a matte glaze vase. The good news was that it did clean the bowl. The bad news is that it cleaned off some of the glaze in the process. The suggestion would be to test a small area before using Oxi Clean.

WD40 has been recommended to use in getting “sticky” things off pottery, including putty.

NEVER USE CHLORINE BLEACH! This will destroy the pottery. It literally eats it from the inside out and it may cause the glaze to flake.

NOTES: Use great care with any cleaning method. It’s a good idea to try the method on an inexpensive piece before attempting to clean valuable pieces. Make sure that you carefully look over any piece that you are going to soak. If a restoration or repair has been made on a piece of pottery, chances are the piece could be ruined by one or more of these cleaning processes.