Yesterday I was testing pH and TA on a must and, AGAIN, I got low pH
(3.35) and low TA (0.4%). This had happened to me previously with
another batch. I know that my digital pH meter was OK because I
calibrated it, so I decided to take a look at the NaOH. This came from
a kit that I bought at the local winemaking supply shop. You know, one
of those boxes for $7 with a syringe, a cup, a small bottle of
phenoftalein, and a bottle of 0.2N NaOH. Except that instead of the
phenolftalein I use the pH meter to titrate to a pH of 8.2, and instead
of the syringe I use a pipette.

I know that NaOH gets weaker over time due to contact with air, but
that would mean that my measurements would likely be artificially high
instead of too low. So I decided to do an experiment. I dissolved 5 g.
of tartaric acid in 1 l. of water. I figured that my TA test should say
0.5%. I do the test and I read a TA of 0.35%. I do it again, this time
with the color indicator instead of the pH meter, and I get the same
result. Then I decided to try another bottle of 0.2N NaOH that I bought
at the same store, and this one didn't do anything! It might as well
have been water in the bottle.

So one bottle of sodium hydroxide gave me a value that was way too low,
and the other was useless. Has this happened to other people? Where can
I buy NaOH that is of good quality, and that has a date on the bottle?
I'd rather buy 1N instead of 0.2N so that it will keep better.

Thanks in advance for any suggestions.

Franco

"Franco" > wrote in message
oups.com...
> Yesterday I was testing pH and TA on a must and, AGAIN, I got low pH
> (3.35) and low TA (0.4%). This had happened to me previously with
> another batch. I know that my digital pH meter was OK because I
> calibrated it, so I decided to take a look at the NaOH. This came from
> a kit that I bought at the local winemaking supply shop. You know, one
> of those boxes for $7 with a syringe, a cup, a small bottle of
> phenoftalein, and a bottle of 0.2N NaOH. Except that instead of the
> phenolftalein I use the pH meter to titrate to a pH of 8.2, and instead
> of the syringe I use a pipette.
>
> I know that NaOH gets weaker over time due to contact with air, but
> that would mean that my measurements would likely be artificially high
> instead of too low. So I decided to do an experiment. I dissolved 5 g.
> of tartaric acid in 1 l. of water. I figured that my TA test should say
> 0.5%. I do the test and I read a TA of 0.35%. I do it again, this time
> with the color indicator instead of the pH meter, and I get the same
> result. Then I decided to try another bottle of 0.2N NaOH that I bought
> at the same store, and this one didn't do anything! It might as well
> have been water in the bottle.
>
> So one bottle of sodium hydroxide gave me a value that was way too low,
> and the other was useless. Has this happened to other people? Where can
> I buy NaOH that is of good quality, and that has a date on the bottle?
> I'd rather buy 1N instead of 0.2N so that it will keep better.
>
> Thanks in advance for any suggestions.
>
> Franco

Franco,
It sounds like you have a supplier problem rather than a sodium hydroxide
problem. I have ordered sodium hydroxide from "Presque Isle Wine Cellars"
( www.piwine.com ) for many years and I have found them to be very reliable
and helpful.
Lum
Del Mar, California, USA

Thanks Lum. I just ordered from Presque Isle a bottle of 0.1N NaOH and
another of 0.1N potassium acid phthalate to standardize.

Franco,
One other thing. Don't forget to heat the sample first, it does affect
the TA end results. You don't have to boil but I do. I put 50 ml in a
microwave for around 30 seconds. As soon as I see boiling I cool and
add distilled water back to 50 ml. It makes a difference.

I never see any references to prepping like this for pH measurement.
Since I want to remove the CO2 in the real wine too, I test the pH of
this sample, it can be different by 0.1 pH units. I guess what I
should do is measure one last time right before bottling, it may be a
good indicator of CO2 saturation.

I rack pretty gently so sometimes have more CO2 left in the end than I
prefer, it's a pain to degas. I'm starting to rack the reds more
roughly, both to degas and expose it to a little bit of air. I used to
use two racking canes on both reds and whites, one in the receiving
vessel to let the wine trickle in from the bottom up. I don't think
that makes sense anymore at least with reds.

Joe

Another option for getting the solution - a friend of mine makes his
own from lye he gets from a hardware store. You can make it fresh, as
much as you want when you need it. I don't know the ratio to water to
make up the 0.1N standard, but I can ask.

Pp

I assume that was and LD Carlson kit. There was a bunch of discussions
over on winepress about it and they have since recalled those kits.


Franco wrote:
> Yesterday I was testing pH and TA on a must and, AGAIN, I got low pH
> (3.35) and low TA (0.4%). This had happened to me previously with
> another batch. I know that my digital pH meter was OK because I
> calibrated it, so I decided to take a look at the NaOH. This came from
> a kit that I bought at the local winemaking supply shop. You know, one
> of those boxes for $7 with a syringe, a cup, a small bottle of
> phenoftalein, and a bottle of 0.2N NaOH. Except that instead of the
> phenolftalein I use the pH meter to titrate to a pH of 8.2, and instead
> of the syringe I use a pipette.
>
> I know that NaOH gets weaker over time due to contact with air, but
> that would mean that my measurements would likely be artificially high
> instead of too low. So I decided to do an experiment. I dissolved 5 g.
> of tartaric acid in 1 l. of water. I figured that my TA test should say
> 0.5%. I do the test and I read a TA of 0.35%. I do it again, this time
> with the color indicator instead of the pH meter, and I get the same
> result. Then I decided to try another bottle of 0.2N NaOH that I bought
> at the same store, and this one didn't do anything! It might as well
> have been water in the bottle.
>
> So one bottle of sodium hydroxide gave me a value that was way too low,
> and the other was useless. Has this happened to other people? Where can
> I buy NaOH that is of good quality, and that has a date on the bottle?
> I'd rather buy 1N instead of 0.2N so that it will keep better.
>
> Thanks in advance for any suggestions.
>
> Franco
>

Franco -
A couple of months ago there were similar posts on another
winemaking forum, and it turned out that the NaOH solution supplied
with many of the L.D.Carlson acid test kits in the past year was
significantly stronger than it should have been. If the kit was
designed for 0.2N NaOH, it seemed like the actual strength was around
0.35 N or so -- close to twice as strong as it should have been,
resulting in erroneously low acid measurements. Carlson discontinued
sales of their product (which they don't manufacture, they just
distribute) until they could either assure better accuracy, or find
another supplier. I'm not sure whether they have resumed distribution
of these kits yet.

Carlson seemed to be trying to handle the whole thing responsibly,
but they have no way to contact all the folks who bought their kits
over the past year or more, and several winemakers who had added a lot
of acid to their wines based on these bad test results were pretty
irate about the whole thing.

Here is a URL to the thread discussing this problem, including
comments from Rob Kight, General Manager of L.D. Carlson.

http://www.winepress.us/forums/index...#entry121 912

So far as I have heard, the problem did not affect other sources (e.g.,
Presque Isle), but I think L.D.Carlson does sell a lot of these kits
through local homebrew outlets, so I'm sure it affected a lot of folks,
many of whom may not know it yet. :-(

Doug

Yes, I have the Carlson kit. Piece of shit. I'm gonna send them my very
tart blueberry wine and ask them to shove it up their asses. I've
learned a lesson. Maybe if I cold stabilize it and get a lot of
tartaric acid to precipitate I can salvage it.

You may want to blend it with something else, that really works well.

I doubt you can pull much more than 1g/l out cold stabilizing. If the
pH was at 3.2 or lower you could try calcium or potassium carbonate but
3.35 is not bad. Maybe do both, some potassium carbonate to reduce it
1g/l and then cold stabilize. A little sugar goes a long way on tart
wine too.

Don't do anything until you get good chemicals. A tart wine will keep
practically forever, you could have worse problems...

Joe

>a friend of mine makes his own from lye he gets from a hardware store
>
>I don't know the ratio to water to make up the 0.1N standard, but I can ask

I'd like to know more about how he does this and why. Is he doing this
to ensure that he always has fresh solution? To save money? Some other
reason? How reliable are the results?

Erroll

Erroll Ozgencil wrote:
> >a friend of mine makes his own from lye he gets from a hardware store
> >
> >I don't know the ratio to water to make up the 0.1N standard, but I can ask
>
> I'd like to know more about how he does this and why. Is he doing this
> to ensure that he always has fresh solution? To save money? Some other
> reason? How reliable are the results?
>
> Erroll

Both money and reliability of results although reliability is by far a
bigger concern - his argument was that people get cheap in wrong
places, use expired solutions to save money and end up with unbalanced
wine as a result.

The results should be very reliable - the solid form is way more stable
if stored properly and the cost is minimal so there is no incentive to
keep outdated solution. I've just found on the net that 0.1N solution
is 0.4% NaOH to 99.6% water by weight, so it would take only about 0.5g
NaOH to make the 120 ml or so batch that comes in the acid testing
kits.

I'm happy with the premade solutions I'm getting and don't have
problems with the results, so I haven't bother, but it might be a good
alternative for people who do have problems or can't get premade
solutions locally.

Pp

If by "solid form" you mean pure NaOH, I think that it is extremely
toxic. A biologist friend of mine told me that he got dizzy handling
NaOH pellets even though he was wearing all protective gear and he had
a extraction hood pulling the fumes out of the room.

Lye is sodium hydroxide, we used to buy it in 55 gallon drums and took
no extraordinary precautions other than to keep it away from water,
it's exothermic. We used to use it on 100 year old drains (shudder).
We wore gloves and eye protection and just dumped it down slow drains.
I'm surprised that is still legal but if lye is still available in
hardware stores I can't imagine another use for it, it's pretty
reactive stuff.

One problem with making up your own solution is minor but should be
mentioned, it's very hygroscopic. If you buy some and just weigh it
out to use it you can be off a bit because once opened it absorbs
moisture. I do think 4 grams in one liter is correct for 0.1N but have
never made any myself. (I got this from a chemist, I'm not one so
can't speak with authority on the subject.)

It's always a good idea to calibrate it no matter how you get it.


Joe

Franco wrote:
> If by "solid form" you mean pure NaOH, I think that it is extremely
> toxic. A biologist friend of mine told me that he got dizzy handling
> NaOH pellets even though he was wearing all protective gear and he had
> a extraction hood pulling the fumes out of the room.

> I'm surprised that is still legal but if lye is still available in
> hardware stores I can't imagine another use for it

I got curious and did a little poking around. It looks like people who
make their own soap use lye, and it's for sale at place like these:

http://www.texasnaturalsupply.com/tns_039.htm
http://www.snowdriftfarm.com/dry.html
http://www.chemistrystore.com/Sodium_Hydroxide.htm

It may not be commonly available in hardware stores anymore. A drain
cleaner called Red Devil, which was 100% lye, has been discontinued.

It looks like Presque Isle sells 16oz of NaOH solution for roughly the
per pound price of dry NaOH. How many grams in a pound again? Isn't
that enough to make about 100 liters of solution? Might be worth doing.

Erroll

If I were going to make my own I would get it from a chemical house
like Sargent Welch or Fisher Scientific but you are right, this is
incredibly cheap. Fishers is better than 97% pure but sells for $40 a
pound. It's still cheaper if you have an accurate balance.

Joe