a versatile surfactant that kills bubbles

From: Ryuji Suzuki ^lt;[email protected]>
Date: 01/16/05-03:38:52 AM Z
Message-id: <20050116.043852.45745932.lifebook-4234377@silvergrain.org>

It's nothing major but it may be of great practical use for some people.

I've been using Triton X-100 for many uses without thinking but a
while ago I was so frustrated. It gives only ok spread of emulsion
when coating unless bubbling amount is used. I've tried some defoamers
but too much defoamer is a quick way to get unevenly coated
spots. Anionic surfactants of sulfonate types (e.g. Triton X-200)
seems to be very effective in improving spread of emulsion, but I
found these way too bubbly for brush coating.

Here's the silver bullet I found. Tergitol L-62. This is a polyether
polyol (nonionic) of MW 2500. It has faintly sweet smell and almost
zero toxicity. It has a decent wetting activity AND defoaming effect,
especially at temp of 30 to 50C. Wetting could be further improved by
addition of another surfactant like Triton X-100 (though I'd rather
use Tergitol TMN-6 if I were shopping for surfactant today).

It doesn't do anything special but it reduced the level of frustration
at a couple of steps in silver gelatin emulsion making as well as
coating in my practice. In particular, bromide emulsion worked well
with unsized Fabriano Artistico Extra White HP. I never thought it
would work like that easily before. It's a WD-40 of darkroom work.

Just FYI -

Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)
Received on Sun Jan 16 03:39:29 2005

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