On Mon, 19 Sep 2005 18:48:47 +0100, ceg
wrote:

[sugar soap]

just wondered if it goes off with age, as this is stuff had in the
garage for last year or so... it doesnt seem to pong as much as i
remember??

Sugar soap may be scented, and this will be fugitive, (if you can smell
something it must be at least slightly volatile) but the underlying
surfactants are relatively stable with respect to time. Are you using hot
water? The compounds used in modern (i.e. the last 20+ years) are
appreciably less soluble in hot water than cold.

The old starch pastes required cooking up to solubilise the starch. Then
along came cellulose ether types which needed pouring into hot water to
prevent clumping and being left to cool with occasional stirring. Then the
technology came along to coat the cellulose with glyoxal, which dissolves
relatively slowly, allowing the powder to be added to cold water and be
stirred for a few minutes until the paste was ready. The latest
generations are based on starch ethers, a chemically modified starch
requiring no boiling, just stirring into cold water. The high-strength
types may also contain redispersible PVA powder. I will leave the readers
to fathom why the market leading (when I worked in the field) Celacol WA
was so designated.

John Schmitt

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