# chemical diff between different viscosity celluloses

**URL:** <https://boards.straightdope.com/t/chemical-diff-between-different-viscosity-celluloses/465371>\
**Category:** Factual Questions\
**Created:** [September 26, 2008, 5:53pm UTC](https://boards.straightdope.com/t/chemical-diff-between-different-viscosity-celluloses/465371 "2008-09-26T17:53:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\
**Post date:** [September 26, 2008, 5:53pm UTC](https://boards.straightdope.com/t/chemical-diff-between-different-viscosity-celluloses/465371/1 "2008-09-26T17:53:17Z")

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Yet another chemistry question

I can get methyl cellulose or other cellulosic derivatives at various viscosities. Right now I have 3 containers of methyl cellulose (15cP; 400cP; and 1500cP) What chemically makes them different. Is it the degree of -OH or methyl substitution? is it the MW?

Does anyone here know for sure?

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**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\
**Post date:** [September 26, 2008, 6:34pm UTC](https://boards.straightdope.com/t/chemical-diff-between-different-viscosity-celluloses/465371/2 "2008-09-26T18:34:48Z")

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It’s the molecular weight.  
From the info sheet available from Aldrich for Methocel A (a.k.a. methyl cellulose): The degree of substitution for all are the same at 1.5-1.9

cPs … Molecular weight  
15…14,000  
25…17,000  
400…41,000  
1500…63,000  
4000…88,000