6306Re: [Marbling] Re:paper problems
- Dec 2, 2011Hi Caryl,
No, the soda water treatment didn't replace alum. I buy soda water at the supermarket (in Australia). Perhaps it is called something else in other places? I soaked the paper in soda water (straight from the bottle, at room temp), dried it, then alumed, then dried, then marbled on the same day.
Why did I think of doing this? When I first tried marbling, I never knew whether things weren't working due to the paper or for another reason. I ended up buying old paper from an Op Shop (short for Opportunity Shop, or a charity shop) and successfully marbled with that. That way, I knew that I could marbled properly. I then wondered what would happen if all the paper manufacturers made paper that didn't work for marbling. What a horrible thought! I wanted to find a way to make "bad" paper into good paper. So, I went to a university library and looked up some old journals put out by the Technical Association of the Pulp and Paper Industry (TAPPI) and looked for articles on alum, calcium carbonate and anything else I thought might be relevant. I found that when aluminium salts (like alum) dissolve in water, they combine with the water and exists in many different forms. Exactly what form and how much depends on the concentration, the temperature and the
pH. I found it interesting that, when the pH approached neutral, the form was aluminium hydroxide (or something similar incorporating sulfate), and this is a white powder. I had found that a white powder formed on some of my papers after they had been alumed. I wondered whether the reason why some of the newer papers might not be working was because the alum could not get into the "correct form" because the pH of the paper was too high. I have no idea what this "correct form" is, because alum exists in lots of them at lower pHs. I am certain that the white precipitate is not the correct form for marbling! In this form, the aluminium is not interacting with the paper fibres at all, rather it is forming a white powder on the paper.
I know that the modern papers contain a buffer that resists small changes in pH. I don't know how big a small change is, I think you need to know exactly what the buffer is. I thought that soaking the paper in something that was a mild acid, like soda water, might allow the alum to exist in the "right form". I know the buffer will be working to remove the acid, but how fast does it do this? I don't know! I certainly made paper that didn't work on a particular day, work that very same day by treating it with soda water, then alum. But, perhaps it didn't work initially for another reason? I also tried other acids (tea (tannic acid), soluble aspro (salicylic acid), and even denture cleaning powder (sulfamic acid, and no, I don't wear dentures!). I found soda water worked best...it is cheap and isn't harmful.
This is only my theory, I have no idea if it is correct. I certainly welcome any comments. I will be having another try over the Xmas/New Year break and will report back after that.
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