I don't think the distillation behavior of IPA or ethanol in terms of the percentage water composition of the azeotrope is in any way directly linked to its "hygroscopic" behavior at room temperature. The percentage of water in the distillate is established at an elevated temperature where the alcohol-water mix comes off the still at a single temperature and fixed concentration.
Whether a substance is hygroscopic relates to its tendency to absorb water from ambient air or from substances in contact with it. Since these alcohols contain water you then have an equilibrium question in the balance between water molecules leaving (evaporating from) the alcohol/water mix and water molecules in ambient air entering the alcohol at the exposed surface, which depends on the ambient humidity level. It seems highly unlikely that this would necessarily preserve the azeotropic concentration or that it would absorb water vapor from ambient air on a net basis.
Whether a substance is hygroscopic relates to its tendency to absorb water from ambient air or from substances in contact with it. Since these alcohols contain water you then have an equilibrium question in the balance between water molecules leaving (evaporating from) the alcohol/water mix and water molecules in ambient air entering the alcohol at the exposed surface, which depends on the ambient humidity level. It seems highly unlikely that this would necessarily preserve the azeotropic concentration or that it would absorb water vapor from ambient air on a net basis.
Yes, that seems reasonable.
Yes, I was wondering where the equilibrium lies at room temperature, and at what %age the mixture stops being hydroscopic? Not for air/water vapour, but for contact with vinyl groove surface as to water which might be tied into the pvc structure ?
As to Bill's 'constant boiling temperature' for IPA/water mixture, from somewhere I weakly recall at room temperature/pressure vapour pressure is equal at about 25% IPA - can anyone verify that ?
Behind my question is an interest in whether cleaning with ipa/water mix might, under some conditions, net remove water from vinyl's surface or structure. And, if so, whether that might be concentration dependent?
LD
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The best flud I got from experience is made of (for 250 ml):
- 20 ml of "Endozime AW plus" (an enzimatic product used in surgery to clean up tools from organic contaminants). Manufactured by Ruhof.
- 80 ml of pure Isopropyl (the pharmaceutical, not for industrial use)
- 10 ml of "the art of sound" fluid
- 140 distillated water (pharmaceutical)
I used this fluid with a Loricraft record cleaning machine. I apply the fluid and place the brush on the disc until a thin layer of foam appears (this result of the 10ml of "The art of sound"). With the Loricraft I do not rinse as no residuals are caught by the stylus.
- 20 ml of "Endozime AW plus" (an enzimatic product used in surgery to clean up tools from organic contaminants). Manufactured by Ruhof.
- 80 ml of pure Isopropyl (the pharmaceutical, not for industrial use)
- 10 ml of "the art of sound" fluid
- 140 distillated water (pharmaceutical)
I used this fluid with a Loricraft record cleaning machine. I apply the fluid and place the brush on the disc until a thin layer of foam appears (this result of the 10ml of "The art of sound"). With the Loricraft I do not rinse as no residuals are caught by the stylus.
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