Email digest for the Global Conservation Forum (ConsDistList) egroup. ------------------------------------------------------------------------------------------------------------
1. RE: Calcium sulfate on/in brick 2. RE: historic brass/copper alloy book clasps 3. Tapestry Conservation Internship at Historic Royal Palaces 4. RE: historic brass/copper alloy book clasps 5. RE: Calcium sulfate on/in brick 6. JOB OPPORTUNITY - Assistant Conservator, Paper - The Art Institute of Chicago 7. RE: historic brass/copper alloy book clasps ------------------------------------------------------------------------------------------------------------ 1.From: Sebastiaan Godts Posted: Wednesday July 9, 2025 7:27 AM Subject: RE: Calcium sulfate on/in brick Message: Dear Peter, An effective method is using a mild 3–5 % ammonium carbonate solution, applied with a cellulose poultice. The principle is straightforward. Ammonium carbonate donates carbonate ions that react with the calcium sulfate, converting it to insoluble calcium carbonate and releasing soluble ammonium sulfate: (NH₄)₂CO₃ + CaSO₄·2H₂O → CaCO₃ ↓ + (NH₄)₂SO₄ + 2H₂O The soluble sulfate is then absorbed by the poultice and removed. Use deionized water with ~30–50 g ammonium carbonate per liter. Mix it into cellulose fiber to make a poultice. Pre-wet the brick lightly, apply the poultice, and cover with polyethylene to prevent premature drying. Test application times between 30 min and maximum 2 hours. When the crust is softened, remove the poultice, brush the surface to remove any residual CaCO₃ film and rinse thoroughly with low-pressure deionized water until the conductivity of the rinse matches the initial water, this is critical to avoid salt re-precipitation. Note: freshly precipitated CaCO₃ is soft, chalk-like skin that can be brushed off while still damp, if left to dry, it recrystallizes and hardens, so timing and method optimization is key in the treatment. A few cautions to consider: do not exceed ~5 % solution or overly long application times, both can cause alkaline staining or mild surface etching. Never let the poultice dry in place, this risks back-migration of the ammonium sulfate. I recommend starting conservatively and adjusting based on your brick's porosity and the crust's response. Be aware that if the bricks already contain sodium or potassium ions, the excess carbonate can precipitate as Na₂CO₃ or K₂CO₃ both soluble and destructive, which can cause post-treatment efflorescence and renewed crystallization stress instead of forming the intended stable CaCO₃. If possible it is best practice to analyze the initial ion content, before and after treatment by quantifying Ca²⁺ , SO₄²⁻ ,Cl⁻ , Na⁺ ,K⁺ , Mg²⁺ , NO₃⁻ per weight of dry mass. Others might be able to add or comment on the method, so please verify before carrying this out. This is an important subject not only for heritage objects, but also for new construction which often show gypsum efflorescence at the surface due to the use of soaps or oils in the mortar or additives used during brick manufacturing. I hope helps. Best regards, Sebastiaan ------------------------------ ---------------------------------- Sebastiaan Godts, PhD Conservation Scientist, Monuments Lab Royal Institute for Cultural Heritage (KIK-IRPA) Jubelpark 1, 1000 Brussels www.kikirpa.be ------------------------------ ------------------------------------------- Original Message: Sent: 07-08-2025 18:59 From: Peter Wollenberg Subject: Calcium sulfate on/in brick I have run into an issue with INSOLUBLE calcium sulfate firmly attached to highly absorbent brick. Cleaning tests were done using an array of commonly available commercial cleaners 22 years ago. Almost none worked. Testing of a variety of poultices this year also failed to move any of the salts. They appear to be essentially non-destructive and maybe confined to the surface because they are insoluble. The pattern of staining is nearly unchanged from 22 years ago (the original sin happened in the 90s sometime). Has anyone had any experience with products that are effective at converting this salt into somethings more soluble and removeable? Yes, I have consulted the literature which appears bereft of solutions to INsoluble salts. Peter Wollenberg Wollenberg Building Conservation, LLC 314-645-4949 Fx: 645-4990 [email protected] <[email protected]> 2.From: Renate Mesmer Posted: Wednesday July 9, 2025 8:28 AM Subject: RE: historic brass/copper alloy book clasps Message: Dear Stephanie, I would connect with Brien BEIDLER MADE Bookbinding and Toolmaking <https://www.beidlermade.com> Beidler. He might be able to help with a project like yours. ------------------------------ Renate Mesmer Head of Conservation and Preservation Folger Shakespeare Library Washington United States ------------------------------ ------------------------------------------- Original Message: Sent: 07-07-2025 11:35 From: Stephanie Gibbs Subject: historic brass/copper alloy book clasps Hello, I am looking for a custom fabricator of book clasps and corner hardware, working in brass/copper alloys. They can be based either in the North America or Europe. I have a private conservation client who would like to integrate historically appropriate clasps and corners in a Renaissance book conservation project. Detail and quality of the metalworking is significantly more important than price point; all of the options that I have found have been more theatrical than historic. Any leads appreciated. Thank you, Stephanie [email protected] <[email protected]> 3.From: Mika Takami Posted: Wednesday July 9, 2025 4:43 PM Subject: Tapestry Conservation Internship at Historic Royal Palaces Message: 12-month Tapestry conservation internship at Historic Royal Palaces, U.K. Role type: Full Time, Fixed Term for 12 months Salary: £ 30,163 per annum Based at: Hampton Court Palace We are a team of passional individuals who love and look after six of the most wonderful palaces in the world. We create spaces that inspire and captivate the spirits of all who visit. With the generous support of The Buccleuch Living Heritage Trust and Lord Barnby's Foundation, Historic Royal Palaces is offering a one-year tapestry conservation internship in the Textile Conservation Studio at Hampton Court Palace. This unique opportunity is open to recent textile conservation graduates who are eager to build on their knowledge and practical skills in the specialised field of historic tapestry conservation. The internship will commence in October 2025, with interviews scheduled for 12-13 August 2025 at Hampton Court Palace. About the role The Intern will be based at Hampton Court Palace, where they will gain critical insight and practical, hands-on tapestry conservation skills by working alongside experienced specialists in HRP's long-established tapestry conservation studio. In this unique environment, the Intern will also learn about preventive conservation practices, and conservation science research related to historic tapestries, and processes for condition auditing and documentation. Over the course of 12-month placement, the Intern will focus primarily on hands-on tapestry conservation treatment while also regularly collaborating with a wider multidisciplinary conservation team to conduct condition assessments and assist with on-site display work. About you Applicants should have completed a recognised textile conservation training programme or possess equivalent experience. An enthusiastic interest in tapestry conservation is essential as the successful candidate must be eager to develop their expertise in this specialism over the 12-month placement. Strong digital documentation skills and the ability to maintain detailed, accurate records of the work undertaken are required. Good team-working skills are crucial, and the Intern should be comfortable working at elevated heights. While not mandatory, prior experience caring for historic tapestries in historic houses and heritage settings would be beneficial. The Intern is expected to be an enthusiastic communicator about HRP's conservation efforts, actively contributing to the organisation's communication activities and engaging its diverse audiences. Closing date: 23:55pm, 28th July 2025 Interview date: 12-13 August 2025 Portfolios, including case studies of object conservation, should be submitted electronically by 10 August. Find out more and apply by visiting Tapestry Conservation Intern - Historic Royal Palaces <https://hrp.tal.net/vx/lang-en-GB/mobile-0/appcentre-1/brand-3/xf-87970c3ce728/candidate/so/pm/1/pl/4/opp/1465-Tapestry-Conservation-Intern/en-GB> Historic Royal Palaces is an equal opportunities employer and truly values a diverse workforce. Applications are welcome from candidates regardless of their background. Please be advised that Historic Royal Palaces is unable to provide sponsorship for the UK Skilled Worker visa for this role, as it does not meet the required eligibility criteria for this immigration route. ------------------------------ Mika Takami Treatment Conservation Manager Historic Royal Palaces ------------------------------ 4.From: Babette Gehnrich Posted: Wednesday July 9, 2025 4:45 PM Subject: RE: historic brass/copper alloy book clasps Message: Hi Stephanie, in case you are not familiar with this German bindery, here is the link to their extensive selection of clasps/corners that based on historic models. Perhaps your client might find what he is looking for here, or Mueller might be able to do custom work. Not sure of his English language abilities, though! Best, Babette Buchbeschläge - Buchbinderei Müller <https://mueller-buch.de/index.php/buchbeschlaege.html> https://mueller-buch.de/index.php/buchbeschlaege.html ------------------------------ Babette Gehnrich Chief Conservator American Antiquarian Society Worcester United States ------------------------------ ------------------------------------------- Original Message: Sent: 07-08-2025 05:25 From: Lisa Behrens Subject: historic brass/copper alloy book clasps Hi Stephanie, I can't tell you about a specific manufacturer, but there are craftspeople who make custom metal fittings for historic furniture. They should be able to help you to make anything if you provide them with a reference drawing or photo. Best of luck! Lisa ------------------------------ Lisa Behrens MA Archive Conservator State Archive of Upper Austria Linz Please note that I cannot respond to DMs. Public responses are great. For private exchange, send me an e-mail at [email protected] <[email protected]> ------------------------------ Original Message: Sent: 07-07-2025 11:35 From: Stephanie Gibbs Subject: historic brass/copper alloy book clasps Hello, I am looking for a custom fabricator of book clasps and corner hardware, working in brass/copper alloys. They can be based either in the North America or Europe. I have a private conservation client who would like to integrate historically appropriate clasps and corners in a Renaissance book conservation project. Detail and quality of the metalworking is significantly more important than price point; all of the options that I have found have been more theatrical than historic. Any leads appreciated. Thank you, Stephanie [email protected] <[email protected]> 5.From: Peter Wollenberg Posted: Wednesday July 9, 2025 4:45 PM Subject: RE: Calcium sulfate on/in brick Message: Thank you, Sabastian, for your detailed response. I have had concerns about inadvertently introducing soluble salts where there appear to be none currently. You recommended cellulose poultice versus clay poultices (to avoid more Na and K ions?). ------------------------------ Peter Wollenberg Principal Wollenberg Building Conservation, LLC St. Louis United States ------------------------------ ------------------------------------------- Original Message: Sent: 07-09-2025 06:33 From: Sebastiaan Godts Subject: Calcium sulfate on/in brick Dear Peter, An effective method is using a mild 3–5 % ammonium carbonate solution, applied with a cellulose poultice. The principle is straightforward. Ammonium carbonate donates carbonate ions that react with the calcium sulfate, converting it to insoluble calcium carbonate and releasing soluble ammonium sulfate: (NH₄)₂CO₃ + CaSO₄·2H₂O → CaCO₃ ↓ + (NH₄)₂SO₄ + 2H₂O The soluble sulfate is then absorbed by the poultice and removed. Use deionized water with ~30–50 g ammonium carbonate per liter. Mix it into cellulose fiber to make a poultice. Pre-wet the brick lightly, apply the poultice, and cover with polyethylene to prevent premature drying. Test application times between 30 min and maximum 2 hours. When the crust is softened, remove the poultice, brush the surface to remove any residual CaCO₃ film and rinse thoroughly with low-pressure deionized water until the conductivity of the rinse matches the initial water, this is critical to avoid salt re-precipitation. Note: freshly precipitated CaCO₃ is soft, chalk-like skin that can be brushed off while still damp, if left to dry, it recrystallizes and hardens, so timing and method optimization is key in the treatment. A few cautions to consider: do not exceed ~5 % solution or overly long application times, both can cause alkaline staining or mild surface etching. Never let the poultice dry in place, this risks back-migration of the ammonium sulfate. I recommend starting conservatively and adjusting based on your brick's porosity and the crust's response. Be aware that if the bricks already contain sodium or potassium ions, the excess carbonate can precipitate as Na₂CO₃ or K₂CO₃ both soluble and destructive, which can cause post-treatment efflorescence and renewed crystallization stress instead of forming the intended stable CaCO₃. If possible it is best practice to analyze the initial ion content, before and after treatment by quantifying Ca²⁺ , SO₄²⁻ ,Cl⁻ , Na⁺ ,K⁺ , Mg²⁺ , NO₃⁻ per weight of dry mass. Others might be able to add or comment on the method, so please verify before carrying this out. This is an important subject not only for heritage objects, but also for new construction which often show gypsum efflorescence at the surface due to the use of soaps or oils in the mortar or additives used during brick manufacturing. I hope helps. Best regards, Sebastiaan ------------------------------ ---------------------------------- Sebastiaan Godts, PhD Conservation Scientist, Monuments Lab Royal Institute for Cultural Heritage (KIK-IRPA) Jubelpark 1, 1000 Brussels www.kikirpa.be <http://www.kikirpa.be> ------------------------------ Original Message: Sent: 07-08-2025 18:59 From: Peter Wollenberg Subject: Calcium sulfate on/in brick I have run into an issue with INSOLUBLE calcium sulfate firmly attached to highly absorbent brick. Cleaning tests were done using an array of commonly available commercial cleaners 22 years ago. Almost none worked. Testing of a variety of poultices this year also failed to move any of the salts. They appear to be essentially non-destructive and maybe confined to the surface because they are insoluble. The pattern of staining is nearly unchanged from 22 years ago (the original sin happened in the 90s sometime). Has anyone had any experience with products that are effective at converting this salt into somethings more soluble and removeable? Yes, I have consulted the literature which appears bereft of solutions to INsoluble salts. Peter Wollenberg Wollenberg Building Conservation, LLC 314-645-4949 Fx: 645-4990 [email protected] <[email protected]> 6.From: Sylvie Pénichon Posted: Wednesday July 9, 2025 4:46 PM Subject: JOB OPPORTUNITY - Assistant Conservator, Paper - The Art Institute of Chicago Message: The Art Institute of Chicago is seeking to hire a full-time Assistant Conservator of works on paper to join its Conservation and Science department. For further details about the Art Institute, the position, and to apply, please follow the link below: https://recruiting2.ultipro.com/ART1010AICH/JobBoard/d263cd2b-c4ef-4e10-8876-a2896406a573/OpportunityDetail?opportunityId=23f200fe-7b46-4061-aa97-288ebe4d9684 ------------------------------ Sylvie Pénichon The Art Institute of Chicago ------------------------------ 7.From: Michelle C. Smith Posted: Wednesday July 9, 2025 9:12 PM Subject: RE: historic brass/copper alloy book clasps Message: Hi Stephanie, I wanted to also suggest Joycelyn Merchant, based in Chicago. I learned about her when I attended this symposium <https://web.archive.org/web/20191028172628/https://library.stanford.edu/blogs/stanford-libraries-blog/2019/10/linking-past-forging-future-symposium-chained-bindings-forms>; she collaborated with bookbinder Karen Hanmer on a model of a 15th-century chained binding <https://karenhanmer.com/gallery/p/medievalalum-lc2zk> created for Stanford University Libraries (Joycelyn made the clasps). Here is her website: http://www.bookclasp.com/ ------------------------------ Michelle C. Smith (she/her) San Francisco Public Library [email protected] ------------------------------ ------------------------------------------- Original Message: Sent: 07-07-2025 11:35 From: Stephanie Gibbs Subject: historic brass/copper alloy book clasps Hello, I am looking for a custom fabricator of book clasps and corner hardware, working in brass/copper alloys. They can be based either in the North America or Europe. I have a private conservation client who would like to integrate historically appropriate clasps and corners in a Renaissance book conservation project. Detail and quality of the metalworking is significantly more important than price point; all of the options that I have found have been more theatrical than historic. Any leads appreciated. Thank you, Stephanie [email protected] <[email protected]> You are subscribed to "Global Conservation Forum (ConsDistList)" as [email protected]. To change your subscriptions, go to http://community.culturalheritage.org/preferences?section=Subscriptions. To unsubscribe from this community discussion, go to https://community.culturalheritage.org/HigherLogic/eGroups/Unsubscribe.aspx?UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e&GroupKey=757a8f16-505f-4323-8e74-e376757aa9f7.
