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Caustic Soda vs Soda Ash, using to clean a bast (stem) fiber. Do they have the same affect on the strength of the fiber?


I'm working on a project to clean (dissolve) bark off of some fiber that adheres to the inside of the bark. I've used caustic soda (sodium hydroxide) successfully but it weakens the fiber. Soda ash (sodium carbonate) also works and seems to have less affect on strength but I'm wondering, chemically, if there's any real difference. I don't have access to any gear to accurately measure the real tensile strength.

Thanks for your help.
Shanti Mama
Kathmandu Nepal

lemonie7 years ago
Caustic soda will give you a lower pH, it's more aggressive than carbonate. However, cellulose is more effectively hydrolysed with acid. L
Shanti Mama (author)  lemonie7 years ago
Thanks, lemonie.

I understand that caustic soda is more base and is more aggressive. When you say that cellulose is more effectively hydrolysed with acid... well, can you explain that a little bit?

I'm cleaning an unusual kind of stinging nettle that produces a lovely fiber. When I boil bark ribbons that have been stripped from the plants in as little as a 0.25% solution of caustic soda it seems to take some of the natural feel from the fiber and also weaken it. When I boil ribbons in 0.5% sodium carbonate the results seem to be better. Does this make sense chemically?

I can't tell you how much I appreciate your help.

Well there's more than just cellulose, lignin is another, and I'll guess that this is what the process may be treating. I don't really understand what's happening with your plants.
(You don't want to destroy your fibres so acid is of no use to you)

L