In Volume 33, Issue 57, Maria Melendez Baez asks why iridescent glass became white when consolidated with Paraloid B72 in acetone. This is probably due to a mismatch between the refractive index of the deteriorated glass (the iridescent layer) and the consolidant. Paraloid B72 has a similar refractive index to undeteriorated glass (1.48 compared to approx. 1.5), whereas the refractive index of the iridescent layer is probably nearer to that of silica gel - about 1.43 - so a consolidant with a lower refractive index might give a better result.
Barry Knight St Albans England ****** Unsubscribe by sending a message to [email protected] Searchable archives: http://cool.conservation-us.org/byform/mailing-lists/cdl/
