Email digest for the Global Conservation Forum (ConsDistList) egroup. ------------------------------------------------------------------------------------------------------------
1. RE: Calcium sulfate on/in brick 2. RE: Updated STiCH Carbon Calculator Launch Webinar - July 22nd 3. Le temps des épreuves : réservez votre semaine du 9 novembre 2026 à Paris / The age of photographs symposium: save the date the week of 9 November 2026 à Paris 4. Japanese Papermaking Intensive in Nagaoka, Japan ------------------------------------------------------------------------------------------------------------ 1.From: Sebastiaan Godts Posted: Thursday July 10, 2025 2:16 PM Subject: RE: Calcium sulfate on/in brick Message: Dear Peter, cellulose poultice is the most common for this purpose, clay has some disadvantages, such as, clay often leaves a grey/white film that needs extra scrubbing, it can introduce rusty or brown stains as its natural iron or organics can leach out in the mildly alkaline mix, it can soak up part of the ammonium and slow the reaction, depending on the clay type it can hinder the cleaning mechanism, and yes NH₄⁺ can replace some of the Na⁺, K⁺ or Mg²⁺ in some clays illite's, however the risk is modest of exchangeable Na⁺ , K⁺ , (Mg²⁺), which is easily mitigated by thorough rinsing afterwards. For this purpose I would avoid clays unless further studied ------------------------------ ---------------------------------- Sebastiaan Godts, PhD Conservation Scientist, Monuments Lab Royal Institute for Cultural Heritage (KIK-IRPA) Jubelpark 1, 1000 Brussels www.kikirpa.be ------------------------------ ------------------------------------------- Original Message: Sent: 07-09-2025 12:40 From: Peter Wollenberg Subject: Calcium sulfate on/in brick 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]> 2.From: Tiffani Emig Posted: Thursday July 10, 2025 2:16 PM Subject: RE: Updated STiCH Carbon Calculator Launch Webinar - July 22nd Message: The correct date for this event is Wednesday, July 23rd, as posted on the event calendar and registration page. Please ignore the incorrect date in this post. ------------------------------ Tiffani Emig Deputy Director American Institute for Conservation and Foundation for Advancement in Conservation Washington DC [email protected] ------------------------------ ------------------------------------------- Original Message: Sent: 07-08-2025 11:58 From: Tiffani Emig Subject: Updated STiCH Carbon Calculator Launch Webinar - July 22nd My apologies, it looks like the period was included in the hyperlink. If you had trouble accessing the registration, please use this link: https://learning.culturalheritage.org/products/updated-stich-carbon-calculator-launch <https://learning.culturalheritage.org/products/updated-stich-carbon-calculator-launch> ------------------------------ Tiffani Emig Deputy Director American Institute for Conservation and Foundation for Advancement in Conservation Washington DC [email protected] <[email protected]> ------------------------------ Original Message: Sent: 07-07-2025 11:36 From: Tiffani Emig Subject: Updated STiCH Carbon Calculator Launch Webinar - July 22nd Join project leads Sarah Nunberg, Matt Eckelman, Sarah Sutton, and Henry McGhie for a webinar on Wednesday, July 22nd from 1:00 - 2:00 p.m. ET to explore the features of the newly updated STiCH Carbon Calculator and learn how you can use it to make data-driven decisions to reduce your carbon footprint. Register at https://learning.culturalheritage.org/products/updated-stich-carbon-calculator-launch. <https://learning.culturalheritage.org/products/updated-stich-carbon-calculator-launch.> ------------------------------ Tiffani Emig Deputy Director American Institute for Conservation and Foundation for Advancement in Conservation Washington DC [email protected] <[email protected]> ------------------------------ 3.From: Marie-Angélique Languille Posted: Thursday July 10, 2025 2:17 PM Subject: Le temps des épreuves : réservez votre semaine du 9 novembre 2026 à Paris / The age of photographs symposium: save the date the week of 9 November 2026 à Paris Message: English below ------------------------ Chères et chers collègues, Nous avons le plaisir de vous annoncer que le symposium international « Le temps des épreuves. 50 ans de préservation des photographies » se tiendra à Paris la semaine du 9 novembre 2026. Ce symposium s'inscrit dans le cadre de la célébration du bicentenaire de la photographie. Destiné aux scientifiques de la conservation, conservatrices et conservateurs, responsables de fonds photographiques, conservatrices-restauratrices et conservateurs-restaurateurs des photographies, ainsi qu'aux historiennes et historiens de la photographie, ce symposium contribuera à construire le récit de cinquante années de recherche en conservation-restauration du patrimoine photographique. Il s’attachera à présenter un état des lieux des recherches récentes sur la matérialité des photographies et les conditions de leur conservation. Au plaisir de vous rencontrer à Paris, à l’automne 2026, Le comité d’organisation, Christine Barthe (musée du quai Branly-Jacques Chirac), Céline Daher (Centre de Recherche sur la Conservation), Agnès Gall-Ortik (Département de préservation du patrimoine photographique de la Ville de Paris), Stéphanie Grison (Centre de Recherche sur la Conservation), Marie-Angélique Languille (Centre de Recherche sur la Conservation), Bertrand Lavédrine (Centre de Recherche sur la Conservation), Isabelle-Cécile Le Mée (Ministère de la Culture) et Bertrand Sainte-Marthe (Archives nationales). ------------------------ Dear Colleagues, We are pleased to announce the international symposium, "The Age of Photographs: 50 Years of Image Preservation", that will be held in Paris the week of November 9, 2025. This symposium is part of the events celebrating the bicentenary of the invention of photography. Aimed at conservation scientists, conservators, photographic collection managers, curators, and historians of photography, this symposium on photographic heritage will recount fifty years of research into its preservation, and present an overview of recent research on the materiality of photographs and their conservation conditions. We look forward to seeing you in Paris in autumn 2026, The Organising Committee, Christine Barthe (musée du quai Branly-Jacques Chirac), Céline Daher (Centre de Recherche sur la Conservation), Agnès Gall-Ortlik (Département de préservation du patrimoine photographique de la Ville de Paris), Stéphanie Grison (Centre de Recherche sur la Conservation), Marie-Angélique Languille (Centre de Recherche sur la Conservation), Bertrand Lavédrine (Centre de Recherche sur la Conservation), Isabelle-Cécile Le Mée (Ministère de la Culture) and Bertrand Sainte-Marthe (Archives nationales). 4.From: Giselle Simón Posted: Thursday July 10, 2025 5:52 PM Subject: Japanese Papermaking Intensive in Nagaoka, Japan Message: On behalf of Tim Barrett, please spread the word: October 27-Nov. 1, 2025. Master papermaker Paul Denhoed is offering another Oguni Washi Intensive, Japanese Papermaking Workshop in Nagaoka, Japan, which is located 150 miles NW of Tokyo. Details are here: https://washiacademy.snowbackpress.com/owsoct25/?fbclid=PAQ0xDSwLBjVNleHRuA2FlbQIxMQABp0buOkJwVNihiHgQ9gYlDH8LNaoCNRgVt1aOtRv_pwWikKHtx1o8u1t9btFP_aem_-4dc1fDP0SHvwKtW7kgF4A <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwashiacademy.snowbackpress.com%2Fowsoct25%2F%3Ffbclid%3DPAQ0xDSwLBjVNleHRuA2FlbQIxMQABp0buOkJwVNihiHgQ9gYlDH8LNaoCNRgVt1aOtRv_pwWikKHtx1o8u1t9btFP_aem_-4dc1fDP0SHvwKtW7kgF4A&data=05%7C02%7Cgiselle-simon%40uiowa.edu%7Cd2720362abc04f6b176108ddbf09abb4%7C1bc445959aba4fc3b8ec7b94a5586fdc%7C1%7C0%7C638876770430989392%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=ACT%2FnOQdoAsLa%2FhEqCL3dPBt%2Bae7dzP9bn3MNs34xgA%3D&reserved=0> ------------------------------ Giselle Simón University Conservator University of Iowa Libraries Iowa City United States ------------------------------ You are subscribed to "Global Conservation Forum (ConsDistList)" as [email protected]. 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