Connecting to Collections Care

Good afternoon all, 

30+ years ago my museum accepted a donation of East Asian (we think Japanese) functional and decorative roof tiles. The ceramist in our art department told me that these were probably produced in the 1920s, 30s, or 40s and were handmade and this would make sense given the records we have. Most tiles are unglazed and the ceramist also said the tiles were fired at a very low temperature producing a very black coloring on the outside. There are also a few glazed decorative tiles and it's evident that not all pieces came from the same structure---but there are a lot that were definitely part of a singular structure. 

According to institutional memory, before these pieces were given to the museum they had been buried out at the donor's camp/cabin/cottage and had to be exhumed. Unfortunately, they did not come into the museum clean.

As I'm working to record and process this particular collection, I am stuck on how to best remove all the dirt and debris before putting them in storage. I've done a preliminary removal of the bigger clumps and dirt clods with a brush, but there is still a lot of dirt on some of these. Could anyone provide assistance?

Images have been included if that is helpful.

Thank you! 

Rachel Fugate





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Rachel Fugate
Collections Curator
DeVos Art Museum | Northern Michigan University
906-227-2136 | rafugate@nmu.edu
1401 Presque Isle Ave, Marquette, MI 49855
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Hi, Rachel,

I'm not an objects or architectural conservator but we've had a few pieces like this in our archival collections. If the tiles are unglazed, they're probably porous with dirt and debris that has penetrated beyond the surface. I'd start by using a small handheld vacuum with cheesecloth placed over it and gently vacuuming.  The cheesecloth should prevent any pieces of the tile from being sucked up.  Afterwards I'd use a non-soap cleaning solution or ammonia to gently clean the tiles of any remaining dirt.

Dallas

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Dallas Long
Associate Dean
Illinois State University – Milner Library
Normal IL
(309) 438-3139
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You may want to try using distilled water judiciously to loosen the dirt, before using any chemicals.

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Joshua Herbert
Reference Library Assistant
Louisville Free Public Library
Louisville KY
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Hi Rachel,

George Schwartz with ConservArt replied:

If I'm not mistaken, these are raku (low) fired, stoneware tiles, traditionally used on ancient Japanese roofs. The shape and the stoneware used would vary according to the locally available clay and the various formulas of the makers. The chipped portions reveal a dark interior clay body and the black streaked outside is characteristic of raku firing and is part of the charm. They weren't a consistent color when they were made, as the soot and ash successfully penetrated the porous clay body.

Since they are roof-tiles, getting them wet should not hurt them. They would be quite porous and will absorb the water, but if left to dry, they should return to the color they were before washing.

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Heather Parks
Head of Preservation
Binghamton University Library
Binghamton NY
(607) 777-6207
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Hi Rachel,

As an archaeologist, soil covered ceramics is an occupational hazard. Standard practice nowadays is a simple bucket of tap water and a toothbrush, lay them out to completely dry before storage- they should not feel cold to the touch-if they are still cold, they are still drying. No chemicals, nothing fancy. I haven't had issued washing low fired prehistoric ceramics with this method unless the individual sherd has cracks that are loose, where they 'wiggle' like loose teeth. In that case I wouldn't submerge them, but just use the wet brush to dampen the surface. Do a test to see if the water gets dark, as if its removing a layer of black soot from the firing. Although if these tiles were already buried, they might not have any residue from the firing left and the surface may just be dark gray. After all, they are roof tiles, which are designed to get wet and dry out on their own, although it might take awhile due to the size and thickness of individual tiles. 

I am not an object conservator, but this is how ceramics are washed in archaeology. It would be interesting to hear from an specialist to see how the standard practice in archaeology compares to their expertise.

Hope this helps,

Sheila

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Sheila Oberreuter
Museum Technician
Effigy Mounds National Monument
Harpers Ferry IA
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Rachel
If unglazed the tiles were likely fired in a non-oxygen (closed kiln) environment that turns the red clay dark grey — iron oxide to iron. This is not necessarily a low temperature firing. We see this in bricks with the full range of firings.

Also the chlorine in most tap water is not a preferred additive for historic tile. It may trigger the release of salts and cause a light haze or even a powder on the dry surface. Your museum may already filter it out. If not you can put 5gal buckets of water outside in the sun for a day or two and the chlorine will off gas.

Charles A Phillips, AIA, AIC-pa

433 Phillips Rd
Nacogdoches, Tx 75964


640 Brookstown Ave
Winston Salem, NC 27101


caparch@conservearchitecture.com
336-918-3668

From iPhone

------Original Message------

Hi Rachel,

As an archaeologist, soil covered ceramics is an occupational hazard. Standard practice nowadays is a simple bucket of tap water and a toothbrush, lay them out to completely dry before storage- they should not feel cold to the touch-if they are still cold, they are still drying. No chemicals, nothing fancy. I haven't had issued washing low fired prehistoric ceramics with this method unless the individual sherd has cracks that are loose, where they 'wiggle' like loose teeth. In that case I wouldn't submerge them, but just use the wet brush to dampen the surface. Do a test to see if the water gets dark, as if its removing a layer of black soot from the firing. Although if these tiles were already buried, they might not have any residue from the firing left and the surface may just be dark gray. After all, they are roof tiles, which are designed to get wet and dry out on their own, although it might take awhile due to the size and thickness of individual tiles. 

I am not an object conservator, but this is how ceramics are washed in archaeology. It would be interesting to hear from an specialist to see how the standard practice in archaeology compares to their expertise.

Hope this helps,

Sheila

------------------------------
Sheila Oberreuter
Museum Technician
Effigy Mounds National Monument
Harpers Ferry IA
------------------------------

------Original Message------

Hi Rachel,

As an archaeologist, soil covered ceramics is an occupational hazard. Standard practice nowadays is a simple bucket of tap water and a toothbrush, lay them out to completely dry before storage- they should not feel cold to the touch-if they are still cold, they are still drying. No chemicals, nothing fancy. I haven't had issued washing low fired prehistoric ceramics with this method unless the individual sherd has cracks that are loose, where they 'wiggle' like loose teeth. In that case I wouldn't submerge them, but just use the wet brush to dampen the surface. Do a test to see if the water gets dark, as if its removing a layer of black soot from the firing. Although if these tiles were already buried, they might not have any residue from the firing left and the surface may just be dark gray. After all, they are roof tiles, which are designed to get wet and dry out on their own, although it might take awhile due to the size and thickness of individual tiles. 

I am not an object conservator, but this is how ceramics are washed in archaeology. It would be interesting to hear from an specialist to see how the standard practice in archaeology compares to their expertise.

Hope this helps,

Sheila

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Sheila Oberreuter
Museum Technician
Effigy Mounds National Monument
Harpers Ferry IA
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Rachel,

You might want to contact the Peabody Essex Museum in Salem, MA. Their collection includes the Yin Yu Tang House, a Chinese house built in the late 18th century and used by one family through the early 1980s. They have one of the best collections of both Chinese and Japanese art in this country. Their conservators may be able to help you or at least suggest someone else to contact.

Hope this helps.

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Martha Katz-Hyman
Assistant Curator
Jamestown-Yorktown Foundation
Williamsburg VA
(757) 593-8519
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Thanks all for the bits of advice and information!

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Rachel Fugate
Collections Curator
DeVos Art Museum
Marquette MI
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