Wednesday, March 3, 2010
A CALL FOR HELP FROM A KOVELS READER
This is a reverse tip. Can anyone help with this email request? We have never heard of this problem. "My sister has a huge Roseville pottery collection. She has noticed small chips of paint on her shelves and determined that something is 'eating' her pottery. She said there are tiny holes that are suddenly appearing and hairline cracks in the pots." She goes on to explain that this has happened only since her sister moved to a new house. We suspect there was an abrupt change in the moisture level surrounding the collection, but properly fired pottery should not be affected this seriously. Suggestions are welcome.
Subscribe to:
Post Comments (Atom)
44 comments:
If the cabinets are made of pressed board and NOT all wood the problem may be formaldehyde. A problem not just for the dishes but also for the people living in the house. It is highly toxic.
Your sister may be a victim of sulfer ridden drywall from China. It was bought cheaply during the building boom and is eating away at copper pipes, and generally causing corrosion. Your pottery may be in danger of being seriously damaged.
It might help to know the pattern. We frequently encounter what might be described as "chips of paint" on pieces in Roseville's Rozanne pattern (as well as Weller's Louwelsa). I don't think that's so much a statment of the quality of the pots or firing... but just a less durable finish.
With the more typical patterns (i.e. Magnolia) I wouldn't hazard a guess without pictures or seeing them first-hand.
It sounds like the pottery was washed in a bleach like liquid. You must cut off the air around that. A first good step must be to spray a clear Lacquer glaze in matte and / or gloss , over the whole piece inside and outside . This seals the item from air that is probably causing crystals to form through the normally unseen craze lines and under the outer layer of glaze. The crystals are form from the digestion of the middle layer off clay. Pottery and like items , are formed in 3 layers outside glazing then clay and then by inner glazing. More info coming
Could this be related to the corrosive effects of Chinese-manufactured drywall? See links below.
http://www.cnn.com/2009/US/11/23/chinese.drywall/index.html
http://www.chinesedrywall.com/
Is it a brand new house or 'new to her'? If it is brand new, the walls, carpeting or other construction materials could be outgassing volatile organic chemicals (VOCs) that could be attacking the surfaces of the pots. VOCs are also unhealthy for people and animals to breathe and can cause asthma and other health problems. The first thing I would do is have the air tested.
Remove the pottery from the house immediately until this is resolved!
I could be the plaster board is the chinese board that has been implicated in multiple probles in new hoome. Contact the builder and find out where the plasterboard came from and if it was imported. Search the internet for "Chinese Drywall" or "Chinese Plasterboard" for more. Here is a first hit... http://www.newhomessection.com/blog/chinese-drywall-investigation-in-florida/2009/02/26/
This link may provide a clue: http://www.ashmolean.org/departments/conservation/deterioration/#sect4
Check to make sure the new house does not have Chinese drywall. It will eat pottery. It will also make ypu very sick. Get the pottery out of the house.
Since they moved into a new home maybe they have "Chinese Drywall issues".
I don't know if it is common knowledge but it causes pipes to change colors and corrosive problems.
Someone may have used chlorine bleach to clean the pieces at some time in the past. Using chlorine bleach can slowly disintegrate pottery. I tried this once on a broken pot to see for myself what would happen - it's slowly turning to powder. Alternatively there could be some chemical in the shelves that is leaching into the pottery, but this is a wild guess. I agree that it is unlikely that a moisture or humidity change could create the problem.
Didn't say move from where to where. Different elevations could have lead to possible air bubbles in the pottery are now under pressure and popping.
My first thought is perhaps the lady has been ripped off and was sold some Chinese Roseville copies.
If it is genuine, a drastic and sudden change of temperature might account for some of the damage.
abbey-laird
Some of the piece's may have been restored, and therefor the finish can flake. I would guess it is with only selected pieces. "Cold restoration" can be affected by changes.
More info on crazing problem. This also may have contributed to the problem : The difference in expansion / contraction characteristics which has the inner layer of clay expanding and contracting at a different rate then the inner / outer glaze does. This forms the craze lines you now see. So it could be the combination of craze lines absorbing cleaning liquids that force the outer glaze to crumble. Again , wipe it carefully , to knock off any loose stuff , then spray them. The Lacquer glaze easily comes off later by dipping in acetone , Lacquer thinner or MEK . Lacquer thinner of the three is my choice . Observe the warnings on the chemical cans and Lacquer spray glaze can TOO, wear rubber gloves and approved mask. These may all be available in a auto supply store ( Pep Boys or auto zone or a pro paint store Good Luck
Has the pottery been frozen??? If so any moisture in the clay body will expand and force the surface glaze off the pot
Sounds like glaze pops, which are small round holes in the glaze formed during firing when air bubbles reach the surface of the glaze and burst and can be brought about by changes in temperature, moisture and sea level. The crazing would be caused by the same problems. Does she keep the pottery in a controlled environment?
I have had a similar problem with bits of my collection. Mice ended up being the cause I know this because they were kind enough to leave their calling card. Dropings !!
There is a type of termite that feeds on sheetrock and concrete. Termites infestations are recognizable by the tiny holes your sister describes. The cracks would be caused by damage to the struction of the pots. Since pottery is similar to these two items, is it possible termites have infested her collection?
Did she or her sister at any time clean the inside of the pottery with clorox? This can start a chain reaction within the piece that is destructive to the ceramic itself. It can take years but it will turn the clay to dust. Lime remover can be just as bad, even with a lot of rinsing.
i would call a commercial pottery and ask the question to one of their chemists. Are any other ceramic pieces doing the same thing?
Perhaps it's a chemical reaction to the fumes of the finish within the area where the collection is stored coupled with the amount of humidity. Like since 2004 pressure treated lumber has copper instead of arsenic which has been found to eat up regular metal nails/fasteners (but not stainless steel) and they wonder why home decks are falling down. So a latex or vinyl paint may be creating a chemical reaction. Just a thought.
May be from abrupt change in temperature....and/or humidity. Perhaps the move involved going in and out or storage from warm atmosphere to very cold and then back to warm.
This happened to some of the very old ceramic mugs my mother left me. I washed them in the dishwasher, and after that they started to craze and corrode. They just crumbled. Also, some of the things I had outside suffered through a freeze this winter, and I notice they too are crumbling.
one of my customers had the same thing happening, she found out ,that her grandchildren were throwing darts at the wall!!
john.
fill the items with unscented cat litter that will solve problem of moisture
MOVE BACK TO THE ORIGINAL HOUSE !!!...PROBLEM SOLVED....
My first thought is also chlorine or formaldehyde. Does she use bleach or air fresheners in her house? Bleach fumes can permeate an entire house when used for cleaning or laundry. Not needed for anything but serious medical situations. Air/fabric/carpet sprays and most scented products, ie. candles etc.,have a LOT of formaldehyde in them. Very bad for decorative items and you. Don't use them. There are many safer and healther alternatives.
Don't rule out mold. Mold attacks rocks and plastics.
There are even mold types that attack CD's by getting between the surface and the metallic coating underneath. That's why CD's are not seen as a forever data storage any more.
Although the glaze may be mold proof (maybe someone knows)the clay is not, even fired.
It sounds like acid or some other strong component from drywall that will eat at paint. Mold may or may not be a factor. Remove from the house immediately. I volunteer at a museum and work with archiving. I suggest contacting a reputable conservator at a museum. Marilyn J. Collier
not knowing what kind of shelves the pieces are resting on, my suggestion is to first, check the quality/make-up of the air and
second, to place the pieces on marble shelves instead of wood or painted ones.
If possible question the former owners of the house about any problem like yours they may have had before they moved. Also ask if they recently remodled using the tainted dry wall material. Third I would call a reputable exterminator and ask if he has seen this problem in his line of business.
I was in a similar discussion about brick and chimney pipes last night.
It is almost certainly a mositure issue.
Take a look at a long clay pipe. The sides are glazed to prevent absorbing mositure, but the ends are open enough to let water be pulled in and then expand and "flake" the pottery.
Roseville is not "hard bone" pocelain, but indeed very porous, even under the glaze. And not everything has been sealed.
The change seems sudden, but from my experience with import woods in the Chicago area, a new "Chippendale" piece in raw mahogany could twist and crack after one winter in front of a heater vent.
I suspect that sometime in recent history (perhaps during the move) the pots were allowed to spend time below 32F. Minute amounts of moisture can cause plenty of damage. We learned the hard way by storing some items in our unheated warehouse, and the pots not only started spalling, some even cracked.
If you've ever seen pitted chrome trim on antique cars, it's the same situation. Hard as it is, the chrome has microscopic cracks that let in tiny amounts of moisture. When frozen, they "explode" the surface of the metal, leaving a pitted surface.
When moving or shipping pottery, I suggest it be placed in a sealed container filled with rice, and left there for several weeks (or longer), to allow the rice to absorb the moisture.
Also of note; items shipped or mailed can go into unheated cargo planes too. It can be 100f on the ground, and well below zero up in the sky, then within a few hours be back on the ground at 100f.
I would test the pieces by cleaning off areas affected to see if paint is removable,if it is then you have pieces that have been restored. Temp and pollutants will affect restored pieces. Do not spray over your pieces unless you have a restoration professional examine them . You could harm them more or add to the cost to restore them.
I suggest that sense you just moved into this house that you try to remember what type of conditions that your china was stored in at your old house and recreate the excate conditions. Good Luck. I hope you can save them.
There are many unseen culprits at work in your house...I suspect "pottery poltergeists" are at work here..they seem to target art pottery in particular because of the tasty old Glaze on it gives them a newfound source of creative/artistic energy when they invisibly eat at it...they are very difficult to exorcise and one needs to call in an antique dealer who specializes in Roseville pottery purchases.
I'm with out gassing. Celluloid in a closed space will film over and pit even chromed tools. I'm less concerned with moisture. I'm thinking it's a gas problem not a contact one
I would have the house termite inspected.the problem started after move.
As with the comments by a number of previous posts, I have witnessed the same deterioration of some very nice ceramic pieces my grandfather had placed in his now closed antique shop. He had washed many pieces in a mixture of water, detergent and BLEACH. Over the years, EVERY piece that had been done this way has crumbled to unsalvageable debris. I know of no way to reverse this process. The breakdown of the internal structure of each piece is seen at first as flecks of glaze followed by a powdery residue directly around the area where the piece was stored. The shop, built in the 1960's, had no chinese-made drywall in its' construction.
It could be those nasty bugs that are having a resurgen in the USA: BED BUGS. They make pin point sized holes to lay eggs. So the tiny holes maybe a clue.
the mention of actual cracks leads me to think that the pieces have been repaired and the mentioned off-gassing of the cabinets or sheetrock has reacted to the unfired surface repair that covered the crack (or chip). I don't see cracks appearing without large temp swings or some physical impact. i doubt the off-gassing would cause a crack.
Thanks for all the comments. I am checking on several. Meantme look out for freezing, high humidity, Chinese drywall and bugs. There is also the problem of washing with bleach that all the experts advised for many years.
Terry
it is the truth when someone says "you learn something new everyday"!!!
Post a Comment