Re: Carbol Fuchsin

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From:Mick Rentsch <> (by way of histonet)
To:histonet <>
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Dear Neal,
All Carbol Fuchsin solutions will do this in time because of the high
phenolic content and a tarry sludge will form in the bottom of the bottle.
It will not matter if the solution is ready made or prepared in your own
Lab. Even if you filter out the material it will continue to reappear.
Of the recipes the Kinyoun's Formulation is most prone to this problem
because of its much higher Phenol content, and in fact will not be very
effective after 4-6 months. On the other hand the traditional ZN formulation
appears to be still workable at 18 months to 2 years despite the presence of
the tarry deposit.
Some workers have advocated the use of heat to put the phenol back in
solution along with any salted out fuchsin, and indeed this does appear to
revitalise the solution.
In summary, don't shake the bottle and if effiacy is dropping off heat to
60C for 30 mins and refilter and use. If you get the sludge on slides your
acid alcohol differentiator will remove it.
Regards Mike (Downunder)
-----Original Message-----
From: <>
To: <>
Date: Monday, 4 January 1999 10:40
Subject: Carbol Fuchsin

>Has anyone had problems with 'ready-made' carbol fuchsin.
>Recently our carbol fuchsin has become thickened (like tar) upon filtering.
>It could be something to do with the recent cold weather, but has anyone

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