Me too.  I weight it out in a sterile 50ml tube, and add enough pure,
sterile water (by weight) to make it down to 20%-40%.  Shake it really well
to dissolve, and you'll have a good supply for many runs.  The 20% solution
won't stick in your pipet tip.  Just need to change your calculation a bit.

> -----Original Message-----
> From:	Leek, Adrian [SMTP:ALeek@cytologix.com]
> Sent:	Tuesday, August 29, 2000 12:52 PM
> To:	'Louise Taylor'
> Cc:	histonet@pathology.swmed.edu
> Subject:	RE: MEASURING ACCURATELY
> 
> Louise:
> To measure viscous liquids accurately, I always do it by weight (with a
> calculator to correct for specific gravity, if neccesary).  Actually, with
> modern top-pan balances, it is usually easier to weigh out liquids than to
> use volumetric glassware.
> Good luck,
> Adrian Leek,
> Cytologix Corp.,
> Cambridge, MA, U.S.A.
> 
> 
> 
> -----Original Message-----
> From: Louise Taylor [mailto:louiset@mail.saimr.wits.ac.za]
> Sent: Tuesday, August 29, 2000 03:54 AM
> To: histonet
> Subject: MEASURING ACCURATELY
> 
> 
> 
> Hello histonetters
> 
> I want to ask a REALLY DUMB question: How does one accurately measure out
> Tween 20 ( pipette, measuring cylinder)? It is so  viscous that I always
> doubt that i have washed out/expelled the correct amount.
> 
> Thanks
> louise taylor
> 
> 
> Research Laboratory
> Department of Anatomical Pathology
> South African Institute for Medical Research
> Johannesburg
> South Africa
> 
> 
>