Archaeological Discussion Group

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc. 

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box. 

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use. 

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Original Message:
Sent: 11/21/2022 5:27:00 PM
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc. 

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box. 

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use. 

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Original Message:
Sent: 11/21/2022 6:23:00 PM
From: Julie Unruh
Subject: RE: Consolidants for mud sealings

Hi Suzanne,

Cool you've got 300 mud sealings. I ended up consolidating an unbaked clay object with Primal WS-24 on one of my projects last season. No acetone or ethanol needed for application, though I did end up doing some (minimal) cleaning with acetone afterwards. Of course you'll definitely want do your own tests to see how your clay's going to behave with water. In my case, I felt I could prevent deformation and slumping via controlled application. There was very little darkening/discoloration of the clay after dry. I wouldn't say the thing is indestructible, but it's less destructible. Especially in the heat, I did have concerns about whether penetration would be deep enough to prevent a consolidated skin from flaking off at some point - but that would be the same for every consolidant, and actually an aqueous consolidant might do better on that front than a solvent-based one. Obviously, not reversable.

Julie

Julie Unruh
Conservator of Art and Archaeological Objects
j.unruh@outlook.com
+1 512 843 2123

Original Message:
Sent: 11/21/2022 5:27:00 PM
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc. 

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box. 

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use. 

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Hi Suzanne,

What an amazing discovery! A few years ago I worked on a contemporary unfired clay project, and put together a chart of all the suggestions I found for unfired clay consolidation on the DistList and talking with colleagues. Maybe something in there will work for your project. Link to the free article is below.

Two big pieces of advice I took away from that project:
1) If you decide to consolidate some, consider the molecular weight of the solvent when you pick your mixture over evaporation rate. Larger molecules won't get through the clay pores, e.g. B-72 in acetone (58.8 g/mol) has half the viscosity as B-72 in toluene (92.14 g/mol).
2) Check to see if your consolidant actually made it all the way through your object, not just the solvent. Steve Koob's site recommendation is to use capillary action and place a small amount of the consolidant on the bottom of a sealed container, and place your object in with one side touching the consolidant. As it slowly wicks up the object and nears the top, place a cheap piece of paper towel (not the fancy kind) on the top and weight it with something. When that paper towel is saturated, take it out and let it dry. If still flexible, the consolidant hasn't made it to the top. Put a new piece of paper towel and test again. Once the paper towel dries stiff, you know the consolidant has made it through.

You can download the paper here, the chart is on p. 4: https://www.icom-cc-publications-online.org/4358/From-cuneiform-to-contemporary---The-conservation-of-unfired-clay

Good luck,
Ariel

------------------------------
Ariel O'Connor
Conservator
National Museum of Asian Art
Washington DC
------------------------------

Original Message:
Sent: 11-21-2022 17:26
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc.

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box.

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use.

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Original Message:
Sent: 11/23/2022 12:47:00 PM
From: Ariel O'Connor
Subject: RE: Consolidants for mud sealings

Hi Suzanne,

What an amazing discovery! A few years ago I worked on a contemporary unfired clay project, and put together a chart of all the suggestions I found for unfired clay consolidation on the DistList and talking with colleagues. Maybe something in there will work for your project. Link to the free article is below.

Two big pieces of advice I took away from that project:
1) If you decide to consolidate some, consider the molecular weight of the solvent when you pick your mixture over evaporation rate. Larger molecules won't get through the clay pores, e.g. B-72 in acetone (58.8 g/mol) has half the viscosity as B-72 in toluene (92.14 g/mol).
2) Check to see if your consolidant actually made it all the way through your object, not just the solvent. Steve Koob's site recommendation is to use capillary action and place a small amount of the consolidant on the bottom of a sealed container, and place your object in with one side touching the consolidant. As it slowly wicks up the object and nears the top, place a cheap piece of paper towel (not the fancy kind) on the top and weight it with something. When that paper towel is saturated, take it out and let it dry. If still flexible, the consolidant hasn't made it to the top. Put a new piece of paper towel and test again. Once the paper towel dries stiff, you know the consolidant has made it through.

You can download the paper here, the chart is on p. 4: https://www.icom-cc-publications-online.org/4358/From-cuneiform-to-contemporary---The-conservation-of-unfired-clay

Good luck,
Ariel

------------------------------
Ariel O'Connor
Conservator
National Museum of Asian Art
Washington DC
------------------------------

Original Message:
Sent: 11-21-2022 17:26
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc.

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box.

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use.

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

The British Museum has published on their cuneiform tablet firing procedures - Denise Ling (Senior Conservator, Ceramic Glass and Metals Section) would be a wonderful contact to ask about the BM past and current methods for firing and adhesive consolidation. I believe they only consolidate fragile pieces with a brush or capillary tube - no immersion or saturation of unfired objects if they're unstable.

Here's a 2002 article on their firing techniques, perhaps there are more recent articles as well: https://doi.org/10.2307/1506830

Please report back if you make progress!
Ariel

------------------------------
Ariel O'Connor
Conservator
National Museum of Asian Art
Washington DC
------------------------------

Original Message:
Sent: 11-28-2022 08:30
From: Suzanne Davis
Subject: Consolidants for mud sealings

Thank you so much, Ariel, and the others who have responded. I'll have a look at all this info.

I'm afraid to saturate these entirely via capillary action, or weight them, as I suspect they would dissolve and collapse. But if I do manage to consolidate any of them in a way that seems to work, I'll report back. 

Weirdly, this is the second archaeological project for me where the team has found a massive cache of mud sealings (there are actually 1,000+ in this case, but only ~300 impressed with anything interesting, not sure if I said that). At the other site, the whole city had caught fire and burned after an ancient battle, thus nicely baking the sealings, which today look a bit scorched but are intact and very stable. Which kind of makes me wonder about baking as a treatment. 

thanks again,

Suzanne

Original Message:
Sent: 11/23/2022 12:47:00 PM
From: Ariel O'Connor
Subject: RE: Consolidants for mud sealings

Hi Suzanne,

What an amazing discovery! A few years ago I worked on a contemporary unfired clay project, and put together a chart of all the suggestions I found for unfired clay consolidation on the DistList and talking with colleagues. Maybe something in there will work for your project. Link to the free article is below.

Two big pieces of advice I took away from that project:
1) If you decide to consolidate some, consider the molecular weight of the solvent when you pick your mixture over evaporation rate. Larger molecules won't get through the clay pores, e.g. B-72 in acetone (58.8 g/mol) has half the viscosity as B-72 in toluene (92.14 g/mol).
2) Check to see if your consolidant actually made it all the way through your object, not just the solvent. Steve Koob's site recommendation is to use capillary action and place a small amount of the consolidant on the bottom of a sealed container, and place your object in with one side touching the consolidant. As it slowly wicks up the object and nears the top, place a cheap piece of paper towel (not the fancy kind) on the top and weight it with something. When that paper towel is saturated, take it out and let it dry. If still flexible, the consolidant hasn't made it to the top. Put a new piece of paper towel and test again. Once the paper towel dries stiff, you know the consolidant has made it through.

You can download the paper here, the chart is on p. 4: https://www.icom-cc-publications-online.org/4358/From-cuneiform-to-contemporary---The-conservation-of-unfired-clay

Good luck,
Ariel

------------------------------
Ariel O'Connor
Conservator
National Museum of Asian Art
Washington DC

Original Message:
Sent: 11-21-2022 17:26
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc.

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box.

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use.

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Original Message:
Sent: 11/28/2022 8:31:00 AM
From: Suzanne Davis
Subject: RE: Consolidants for mud sealings

Thank you so much, Ariel, and the others who have responded. I'll have a look at all this info.

I'm afraid to saturate these entirely via capillary action, or weight them, as I suspect they would dissolve and collapse. But if I do manage to consolidate any of them in a way that seems to work, I'll report back. 

Weirdly, this is the second archaeological project for me where the team has found a massive cache of mud sealings (there are actually 1,000+ in this case, but only ~300 impressed with anything interesting, not sure if I said that). At the other site, the whole city had caught fire and burned after an ancient battle, thus nicely baking the sealings, which today look a bit scorched but are intact and very stable. Which kind of makes me wonder about baking as a treatment. 

thanks again,

Suzanne

Original Message:
Sent: 11/23/2022 12:47:00 PM
From: Ariel O'Connor
Subject: RE: Consolidants for mud sealings

Hi Suzanne,

What an amazing discovery! A few years ago I worked on a contemporary unfired clay project, and put together a chart of all the suggestions I found for unfired clay consolidation on the DistList and talking with colleagues. Maybe something in there will work for your project. Link to the free article is below.

Two big pieces of advice I took away from that project:
1) If you decide to consolidate some, consider the molecular weight of the solvent when you pick your mixture over evaporation rate. Larger molecules won't get through the clay pores, e.g. B-72 in acetone (58.8 g/mol) has half the viscosity as B-72 in toluene (92.14 g/mol).
2) Check to see if your consolidant actually made it all the way through your object, not just the solvent. Steve Koob's site recommendation is to use capillary action and place a small amount of the consolidant on the bottom of a sealed container, and place your object in with one side touching the consolidant. As it slowly wicks up the object and nears the top, place a cheap piece of paper towel (not the fancy kind) on the top and weight it with something. When that paper towel is saturated, take it out and let it dry. If still flexible, the consolidant hasn't made it to the top. Put a new piece of paper towel and test again. Once the paper towel dries stiff, you know the consolidant has made it through.

You can download the paper here, the chart is on p. 4: https://www.icom-cc-publications-online.org/4358/From-cuneiform-to-contemporary---The-conservation-of-unfired-clay

Good luck,
Ariel

------------------------------
Ariel O'Connor
Conservator
National Museum of Asian Art
Washington DC
------------------------------

Original Message:
Sent: 11-21-2022 17:26
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc.

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box.

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use.

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------

Hi Suzanne, 

Chiming in a little late here - but this thread just caught my eye with Ariel's response yesterday! At ICOM CC Glass and Ceramics earlier this month we had a student presentation about testing consolidants and application methods on loam fragments, which are a mix of sand, silt, and clay -- the pieces she performed tests on are part of a study collection and are handled for education purposes, so that was a consideration. The paper was an extended abstract, so much contracted version of her Masters project, which included a huge literature review. I'm including the reference here:

Peeters, Jamilla. "A Comparative Assessment of Three Materials for the Consolidation of Inhomogeneous, Unfired Clay." Recent Advances in the Conservation of Glass and Ceramics 2022. ICOM-CC Glass and Ceramics Working Group Interim Meeting in Lisbon, Portugal, 8-11 Nov 2022. 

I can email you (or anyone else who is interested) the paper and her email address if you'd like.

Hope all is well in Ann Arbor! 
Rebecca


------------------------------
Rebecca Gridley
Associate Conservator
Art Conservation Group
Long Island City, NY
rebecca.ec.gridley@gmail.com
------------------------------

Original Message:
Sent: 11-21-2022 17:26
From: Suzanne Davis
Subject: Consolidants for mud sealings

Dear AHN colleagues,
At the end of the last field season, one of the field projects I work for (Jebel Barkal, Sudan) discovered about 300 mud sealings impressed with ancient Kushite seal designs. I have not yet seen them in person, but the excavating archaeologist is worried about their stability and would like to consolidate them. The mud chunks appear to range in size from a small ball (like a bit smaller than a golf ball) to a fist. They are a sandy, silty mud (probably from the nearby Nile) now completely dry after 2,000 years of desert burial, but not fired or baked in any way. The designs they preserve are extremely cool - Kushite gods, etc.

Has anyone else consolidated mud sealings? Do you have any advice or suggestions on materials to use (or maybe a publication to steer me to)? Or do you think it's best to just store them well? My concern about the latter is that they are likely to be handled a lot for photography, research, and show and tell. On the other hand, 300 sealings is a lot of sealings to consolidate and I will most likely triage and do only the most fragile, so storage suggestions are very welcome. Right now they are in polyethylene self-seal bags, in a box.

A couple notes, seemingly unrelated but impacting treatment decisions: Sudan has a very hot, very dry climate, and climate control is not an option at Jebel Barkal. It is difficult to source ethanol in country, but acetone is not a problem. I need to take with me any other materials and supplies I want to use.

Thanks in advance for any advice or suggestions - I appreciate it,
Suzanne

------------------------------
Suzanne Davis (she/her)
Kelsey Museum of Archaeology
------------------------------