Date: Wed, 18 Jul 2001 13:26:23 -0500
From: Dennis K Demcheck <ddemchec@USGS.GOV>
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Refractometers

As far as I can tell, there is really only one low-cost ($150) hand-held
refractometer that is can do what we Humnetters want. It is sold by
Forestry Suppliers and Cole Parmer (both have excellent web pages). It is
a 0-32% sugar (Brix) instrument with automatic temperature compensation
(ATC) over the range of 50-86 degrees F. There are others with different
ranges, but the only 2 hand-held gizmos with ATC are 0-10 % and 0-32%.
Reporting a sugar concentration of "greater than 32 %" is frustrating
as all get-out. I saw a refractometer for $620 that has 3 ranges and
could read 0-90 % sugar. I was shocked to find out it was not
temperature-compensated! In my opinion, ATC is essential, especially if
we're going to be sampling Salvias in December and July. I take an air
temperature reading when sampling to make sure I'm within the ATC range.

Also, there are desk-model refractometers that go as high as $1,000.
The gizmo I'm using (0-32 %) has a resolution of 0.2 %, and an
accuracy of + or - 0.2 %

Dennis Demcheck
Baton Rouge