Gelatin/ Alum sizing: glues for ink, color, and mounting

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    • #14573 Translate
      罗雁 LuoYan罗雁 LuoYan
      Keymaster

      In China, the glue is made from animal skin/ bone. Why is it?

    • #14580 Translate
      罗雁 LuoYan罗雁 LuoYan
      Keymaster

      Amr,

      I believe that gelatin/alum size is the most famous sizing agent in history. Because it is difficult to do industrially, people switched to rosin/alum size which is based on tree resin, but that apparently causes paper to fall apart after some time, which is why people now sell “acid free” paper for archival purposes. I think gelatin/alum size is not “acid free”, but it still lasts forever.

      So the bone/skin glue is used for layering colors in painting. In mounting it seems the flour paste and alum is enough. Is that because the natural glue in the ink sticks will fix the ink in the presence of alum?

    • #14587 Translate
      罗雁 LuoYan罗雁 LuoYan
      Keymaster

      Pepe Valera,

      Aqui también existe ese pegamento de origen animal
      Se obtiene a partir.de cartílagos de animales…se.llama “cola de conejo”, y sale mde ahí, de las partes blandas que contienen colágeno de cualquier animal, sea conejo, vaca…etc…
      Aquí se sigue vendiendo pero su preparación es algo complicada. Asi que se usa poco.

       

    • #14594 Translate
      罗雁 LuoYan罗雁 LuoYan
      Keymaster

      Amr,

       It seems it was mostly used in Europe, whereas in Asia starch/alum sizing was more common. I am not sure which is more robust. The alum is slightly acidic which tends to hydrolyse cellulose fibers. It is thought that the gelatin can buffer the pH somewhat and preferentially reacts with the alum to protect the cellulose. I am not sure if the same effect can be expected with starch.

    • #14685 Translate
      罗雁 LuoYan罗雁 LuoYan
      Keymaster

      We have found this very nice Japan made natural gelatin. It is now available @inkston.

      Traditional Natural Animal Gelatin 三千本胶

       

    • #17637 Translate
      Disciplecharlesrtsua
      Participant

      The Chinese also use baiji (白芨) which is the root of an orchid, also used in Chinese medicine and as a natural glue (to make silk strings for musical instruments like the guqin etc); the glue is released by boiling the roots. It had been used during the mounting process in the past but not any more as I think it turns paintings yellow-brown over time, hence why many Song/Ming Dynasty paintings etc are really brown. It’s like how varnish turns old oil paintings brown after many centuries.

      Hide glue (明膠) is mainly used to bind pigments together and I wouldn’t use it for mounting as the wheat starch paste is sufficient.

      Alum is not much of an adhesive as it is a preserver and waterproofer and has insect repellent properties, so a pinch of it is added to the paste mix.

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