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Question asked 2022-04-03 13:58:46 ...
Most recent comment 2022-04-03 16:41:55
Egg Tempera
Pigments
Solvents and Thinners
Varnishes
Hello,
Please can you help me with following notion.
I just ordered Paraloid B72 in ethyl acetate from Kremer to isolate lean egg tempera (ET) prior to oil glazes and realise I don't know it's ph value. SDS states N/A. Pure ethyl acetate SDS also, while acetone states ph: 5 - 6 (0 mg/cm3; 20°C).
Why I ask this? Is solvent ph important since my ET has synthetic ultramarine pigment which we know to be not compatible with acids?
One conservator answered me that ethyl acetate is very litle acidic and would evaporate fast so there shouldn't be problem with that plas also that binder would protect it.
I would like to get second opinion.
Kind regards,
Damir P.
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Moderator Answer
(brian baade)
While it is true that oil can have acid numbers and there
are other materials like resins that contain acid groups, and yes ethyl acetate
has an acetate group which is slightly acidic BUT you really do not need to
think about pH in a non-aqueous environment. PH has to do with proportions of
H+ and OH- ions in an aqueous environment. PH has no meaning in a non-aqueous
system. Therefore, do not worry about the ultramarine. No whether ethyl acetate
is the best solvent for B-72 is another question. My guess is that it is
perfectly fine but I always use ethanol, xylene, acetone, or a combination of
those.
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