Clayman on thu 17 dec 98
Hey you clay people. I have a question for you. Will being at an elevation of
7703ft. change your reading on a Hydrometer? If so how can you compensate to
get a correct reading. Rocky Mountain Hiiiiigh ...... Colorado.
Thank you reference heads!!
Jav Caniff
Clayman@cshore.com
Paul Monaghan on fri 18 dec 98
Hi Jav,
the simple answer is no so you don't have to worry about it. The
hydrometer actually measures the ratio of specific gravity refernced to
water. It has nothing to do with pressure or pressure altitude.
However, at 7000+ feet the gravitational field is SLIGHTLY less than at
sea level but NOT that you will ntice with any studio instruments.
Since the hjydrometer is just comparing the fluid your measuring with
reference to water it's a wash.
Go for it.
Hope this helps.
Paul Monaghan
WEB2U Productions
The SECRETS are at
http://www.web2u.com/secret
Clayman wrote:
> ----------------------------Original
> message----------------------------
> Hey you clay people. I have a question for you. Will being at an
> elevation of
> 7703ft. change your reading on a Hydrometer? If so how can you
> compensate to
> get a correct reading. Rocky Mountain Hiiiiigh ...... Colorado.
>
> Thank you reference heads!!
> Jav Caniff
> Clayman@cshore.com
Mike Obrien on fri 18 dec 98
I have no idea what happens in altitude with a hydrometer, but I can tell you
this; If you have past experience with a hydrometer use it to get close to
proper viscosity. When you get a slip that works test it with the hydrometer
so you can repeat it. The main idea, it seems to me, is that when you get a
good result, you can repeat your results, time after time after time. The key
to slipcasting is REPEATABILITY. E-mail me if you need info on sodium
silicate/clay/water ratio. Mike.
Tom Wirt on sat 19 dec 98
Subject: Re: Hydrometer in altitude...
>----------------------------Original message----------------------------
>I have no idea what happens in altitude with a hydrometer, but I can tell you
>this; If you have past experience with a hydrometer use it to get close to
>proper viscosity. When you get a slip that works test it with the hydrometer
>so you can repeat it. The main idea, it seems to me, is that when you get a
>good result, you can repeat your results, time after time after time.
As has been repeated here over and over, with a couple of lengthy discussions on
WHY a hydrometer is not good for measuring specific gravity.....you can not get
good s.g. reading in a glaze with a hydrometer. Try this: have 5 different
people measure your favorite glaze with a hydrometer. Then take 5 readings
yourself. All from the same bucket of glaze. You will find wide variation in
readings.
The only accurate method is with weighing a known volume. What you are
measuring is the amount of solids suspended in the water. And that is what you
are looking for with a glaze....how much solids am I depositing with a given
slop over a given time.
Hydrometers are for measuring solutions, not suspensions.
Second best way is with a viscometer cup, as was noted here the last couple of
weeks.
As to altitude...no difference. Hydrometer works because of gravity and the
gravity is the same for both the solution and the hydrometer.
Tom
Gavin Stairs on sat 19 dec 98
Actually...
There is an effect which slightly alters the result, but it isn't gravity.
The hydrometer acts as a balance, and the effect of gravity divides out,
provided it is non-zero: an immersion hydrometer doesn't work in the
microgravity of space. Also, the emphasis is on slight: this will not be
great enough to affect your measurement, so the following is just for fun
and education.
The small effect is from the buoyancy of air. The density is measured by
comparing the buoyancey of water with that of air. Since air is about
500-1000 times less dense than water, this fact is usually omitted in
discussion of practical instruments. However, there will be a small
(<<0.1%) change in the measurement between a sea level measurement and one
done a mile high, since the air pressure, and density, is less at high
altitude. I can't remember the lapse rate, but I guess that a mile up the
air pressure is maybe 10% less than at sea level. So that means that there
is a correction of about 10ppm in the measurement, with the high altitude
measurement being slightly greater.
I told you it was a small effect!
Gavin
Paul Monaghan wrote:
>Hi Jav,
>
>the simple answer is no so you don't have to worry about it....
Correct!
>However, at 7000+ feet the gravitational field is SLIGHTLY less than at
>sea level but NOT that you will notice with any studio instruments.
>Since the hydrometer is just comparing the fluid your measuring with
>reference to water it's a wash.
Also correct: the gravitational change cancels out exactly.
Jav Caniff wrote:
>> ... Will being at an elevation of 7703ft. change your reading on a
>> Hydrometer?
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