Isopropyl Alcohol

devecchi · Oct 5, 2022

Isopropyl alcohol 70% is good for preparing phenidon or Benzotriazole solution 2%. ?

Donald Qualls · Oct 5, 2022

I'd use 90% or higher, if it's available to you. The main reason to make this kind of stock solution (aside from making it easier to accurately measure sub-gram quantities) is to prevent ionization in the present of water -- and the other 30% of that 70% alcohol is -- you guessed it -- water.

I get my isopropyl from the pharmacy section of the local supermarket, and I can get all the 91% I want for around a dollar a bottle. For my uses (this, and cleaning my 3D printer's glass build plate), there's no reason to buy lower concentration.

Marcelo Paniagua · Oct 5, 2022

70% for antiseptic purpose(the extra water actually helps on killing germs) and 90% for phenidone. I have used 90% for preparing POTA developer and it keeps for some months (around 3-4) before turning brown and weird.

By the way, Propylene Glycol give Phenidone a longer shelf life, probably some years.

Marcelo

Sirius Glass · Oct 5, 2022

Donald Qualls said:
I'd use 90% or higher, if it's available to you. The main reason to make this kind of stock solution (aside from making it easier to accurately measure sub-gram quantities) is to prevent ionization in the present of water -- and the other 30% of that 70% alcohol is -- you guessed it -- water.

I get my isopropyl from the pharmacy section of the local supermarket, and I can get all the 91% I want for around a dollar a bottle. For my uses (this, and cleaning my 3D printer's glass build plate), there's no reason to buy lower concentration.

I am finding it harder to get above 90% propyl alcohol in the drug stores.

Donald Qualls · Oct 5, 2022

Sirius Glass said:
I am finding it harder to get above 90% propyl alcohol in the drug stores.

Around here (central NC, USA) 91% is the common higher concentration, but some places it might just be 90%. No notable difference between them. I've seen 95%, but it's much less common.

Marcelo Paniagua · Oct 5, 2022

Sirius Glass said:
I am finding it harder to get above 90% propyl alcohol in the drug stores.

Me too. Not sure if it would make any difference. For water free dilutions, probably Glycol would be better?

Marcelo

BrianShaw · Oct 5, 2022

Marcelo Paniagua said:
… probably Glycol would be better?

Marcelo

Didn’t Tom Hoskinson prove that decades ago?

Marcelo Paniagua · Oct 5, 2022

BrianShaw said:
Didn’t Tom Hoskinson prove that decades ago?

I think so. At least it does a better job than alcohol at keeping Phenidone alive. Never used alcohol higher than 90% so not sure their performance vs glycol.

Sirius Glass · Oct 5, 2022

Marcelo Paniagua said:
Me too. Not sure if it would make any difference. For water free dilutions, probably Glycol would be better?

Marcelo

But glycol is more expensive than water.

Marcelo Paniagua · Oct 5, 2022

Sirius Glass said:
But glycol is more expensive than water.

I mean to keep the phenidone disolved. This will extend the phenidone viability.

Used this once with good results:

Is it possible to develop film for 2 cents a roll?

Daniel Keating provides a recipe for a highly economical and environmentally friendly film developer

silvergrainclassics.com

Marcelo

Donald Qualls · Oct 5, 2022

Marcelo Paniagua said:
I mean to keep the phenidone disolved. This will extend the phenidone viability.

Isopropyl does this, but not as well as glycol. This is mainly because it can't be water free. Other solvents can work for this, too -- Gainer's PC-TEA depends on dissolving both the phenidone and the ascorbate in water-free triethanolamine. That solvent, however, will affect pH of the final solution much more than isopropyl or glycol (it was the only alkali in that developer).

devecchi · Oct 5, 2022

Donald Qualls said:
Userei il 90% o superiore, se è disponibile per te. La ragione principale per fare questo tipo di soluzione madre (oltre a rendere più facile misurare con precisione le quantità inferiori al grammo) è prevenire la ionizzazione nel presente di acqua - e l'altro 30% di quel 70% di alcol è - avete indovinato - acqua.

Ottengo il mio isopropile dalla sezione farmacia del supermercato locale e posso ottenere tutto il 91% che voglio per circa un dollaro a bottiglia. Per i miei usi (questo e la pulizia della lastra di vetro della mia stampante 3D), non c'è motivo di acquistare una concentrazione inferiore.

devecchi · Oct 5, 2022

Donald Qualls said:
I'd use 90% or higher, if it's available to you. The main reason to make this kind of stock solution (aside from making it easier to accurately measure sub-gram quantities) is to prevent ionization in the present of water -- and the other 30% of that 70% alcohol is -- you guessed it -- water.

I get my isopropyl from the pharmacy section of the local supermarket, and I can get all the 91% I want for around a dollar a bottle. For my uses (this, and cleaning my 3D printer's glass build plate), there's no reason to buy lower concentration.

How long will this solution 90% alcohol during in approximately in months?

Donald Qualls · Oct 5, 2022

I've made a 2% phenidone solution in 90% isopropyl, and it was still good several months later. I was using it fairly regularly to mix H&W Control (low contrast speed increasing developer for document films in pictorial usage). I couldn't tell you beyond that, as I was forced out of my darkroom at that point.

Marcelo Paniagua · Oct 5, 2022

Mine went off in about 3-4 months. Probably will last longer on an air free container and storing it in a cold place.

Marcelo Paniagua · Oct 5, 2022

This was the final color of diluted phenidone when it went off. By went off I mean rolls from it turned out with low contrast and generally seemed to be underdeveloped.

Marcelo

eli griggs · Oct 5, 2022

Has anyone tried maximum proof 190 or 189 Everclear, an ethanol?,

It's a 95% grain alcohol and I use it in other areas, like making shellac, cleanup, etc and it works fine for those things.

I believe I've used it in some photo applications as well but nothing critical.

gordrob · Oct 7, 2022

I got four pack of 500ml bottles of 99% isopropyl alcohol from a local pharmacy a few years back and use it to mix up a 1% or 2% Benzotriazole solution for old fogged film and papers. It seems to keep well in solution and haven't had any problems with it so far.

mrosenlof · Oct 7, 2022

I got some (claimed) 99% isopropyl from Amazon a couple of months ago. I think it was the "fresh" Amazon, so probably came from the local Whole Foods. I see the OP is in Europe, so might not help.

I have used both propylene glycol and "denatured alcohol" which in the US is Ethanol with enough other stuff -- mostly Methanol -- added to make it undrinkable. Fairly cheap (for denatured alc) at the hardware store and Phenidone lasts a long time in it.

My current choice is propylene glycol. I have a heated magnetic stirrer which makes dissolving it go fairly quickly. Shelf life easily > 1 year.

GLS · Oct 21, 2022

Donald Qualls said:
Isopropyl does this, but not as well as glycol. This is mainly because it can't be water free.

This isn't true. 99.9% (or higher) purity IPA is readily available.

Donald Qualls · Oct 21, 2022

GLS said:
This isn't true. 99.9% (or higher) purity IPA is readily available.

Not where I live. The highest I've seen (North Carolina) with any frequency is 91%.

GLS · Oct 21, 2022

Donald Qualls said:
Not where I live. The highest I've seen (North Carolina) with any frequency is 91%.

You can buy it from Amazon.

Sirius Glass · Oct 21, 2022

Donald Qualls said:
Not where I live. The highest I've seen (North Carolina) with any frequency is 91%.

I found that hard to find in California. All that most places have is in the 70% to 80% range. Since I am no working in a chemistry laboratory I do not need reagent quality.

Donald Qualls · Oct 21, 2022

Sirius Glass said:
Since I am no working in a chemistry laboratory I do not need reagent quality.

No, but for some photographic or home purposes the less water the better. For instance, I use 91% for build plate cleaning on my 3D printer.

Sirius Glass · Oct 21, 2022

Donald Qualls said:
No, but for some photographic or home purposes the less water the better. For instance, I use 91% for build plate cleaning on my 3D printer.

I clean my plates in the dishwasher.

Isopropyl Alcohol

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