Isopropyl Alcohol for Cleaning LPs

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#102
Johnny2Bad said:
Alcohols absorb water from the atmosphere. The stable concentration is about 95%; if you have a higher concentration, as soon as you crack the seal, it will absorb water and self-dilute to the lower mixture.

At my drug store, they sell 94%, not 99. In fact I would be suspicious of any alcohol that claims to be higher than 95%.
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Your suspicions aside, the Pure Standard Products product I use is labelled 99% and if I were to leave the bottle uncapped, it may well eventually end up at the same concentration as your ethanol which, it should be noted, also absorbs water.

Given that I open the 500ml bottle and add it directly to 2 liters of distilled water, I expect it reaches and immediately passes the 95% dilution en route to the 20% dilution of my cleaning solution.

It costs considerably less than unadulterated ethanol and doesn't have any of the variety of adulterants added to make ethanol toxic and therefore available for purchase without a license.

If there is some actual evidence beyond opinion that ethanol is a better product in the application I'd certainly consider changing, but in all the many incarnations this discussion has seen in all the venues where it is discussed, I've yet to see any.
 
#105
Ethanol can only be distilled as an azeotrope of ethanol and water that is about 95% ethanol. In order to get higher ethanol concentrations current technology is to use a molecular sieve to separate the water fraction...this is commonly used in ethanol destined for use as a motor fuel as the water fraction is undesireable.
 
#108
tvi said:
A_model_approach_for_finding_cleaning_solutions_for_plasticized_poly_vinyl_chloride_surfaces_of_collections_objects

Furthermore, it was found that organic solvents extracted plasticizer at all of the cleaning time durations, so it may not be appropriate to use pure organic solvents on plasticized PVC for any type of cleaning. On the contrary, mixtures of organic solvents with deionized water may be considered, since they seemed not to extract plasticizer when used in certain proportions.
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If you mix Isopropyl alcohol with salt, the water will dissolve the salt and separate from the alcohol. I wonder if mixing water with the alcohol might make it incompatible with the plasticizers in a similar way?

PVA/wood glue is interesting, but IIRC the problem is that it contains aluminum chloride, which doesn't sound good. Rinsing it off is a good idea I think. I wonder if there is something it could be replaced with that is harmless to records?

"Photographic surfactant" is probably the same kind of thing as Nonidet N40 or Tergitol/N95.
 
#110
luckythedog said:
So, you mean 95% isopropyl is not hygroscopic, ie will not leach water from vinyl it is applied to, but 100% is ??

LD
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Not exackly, LD.

My understanding of the previous posts is that 100% IPA will absorb moisture from the atmosphere (unless you happen to reside in Death Valley) so that it becomes 95% pretty quickly. But it stops there - it doesn't absorb more water to go less than 95%.

But we add water - distilled, preferably, IMO - to make up the cleaning solution containing 25-50% IPA. So when this is applied to the LP - no, the 25-50% IPA doesn't leach water from the vinyl it is applied to.

If you were stupid enough to try to apply 100% IPA to an LP:
1. it probably wouldn't be 100% by the time it hit the record's surface, and
2. it would continue to absorb moisture from the atmosphere - not the vinyl - until it got to 95%.

Andy
 
#111
The 95% number was for ethanol and that is the concentration of ethanol and water that forms an azeotrope in distillation...so that is the highest concentration of ethanol that can be obtained through distillation. Isopropanol behaves similarly but the azeotrope concentration is 91% by volume isopropanol.
 
#113
andyr said:
.... it would continue to absorb moisture from the atmosphere - not the vinyl - until it got to 95%.
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Indeed, 95% doesn't seem plausible........

But I'd be interested in the %age at which Isopropyl stopped being hydroscopic, ie not leaching water eg from contact with vinyl...........

AFAIK Isopropyl is a contact drying agent, and its mixture with water evaporates both fractions faster than just water alone. I'd heard a mixture about 25% evaporates both fractions at the same rate, ie concentration of remaining mixture doesn't change on evaporation, ie drying. Then the concentration of any residue or surface ingress might tend toward 25%, one might think..........and I wondered if 25% might be hydroscopic?

LD
 
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#117
Kay Pirinha said:
Is there proof for the claim that is no hygroscopy at IPA (or ethanol) concentrations below the azeotrope? What's the correlation between the boiling point minimum and the ability to get more diluted by taking up moisture from the air?

Best regards!
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Would you mind explaining why you raised this question ... I cannot see the relevance, relative to LD's claim that IPA will leach water out of vinyl (given that people use only 20-50% IPA mixture to clean records)?

Andy
 
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