Re: Mylar as base for carbon tissue
s carl king (sanking@hubcap.clemson.edu)
Sun, 21 Apr 1996 15:20:05 -0400 (EDT)
> >>
> >
> >Sandy,
> >
> >I've have no personal experience with Mylar but your note brought to mind
> >some published information that might be of help. An old TAB book titled
> >"How To Make Old-Time Photos" by John McDonald and Melba Smith Cole
> >discusses a wet carbon method in Chapter 4 which utilizes Mylar. I believe
> >there is an expired patent on this process, if I have a little time I'll
>
> U.S. Pat. 2,381,234 (Oct. 22, 1943)
>
> The patent was worthless anyway since the "invention" was covered in a
> French patent of 1855.
>
> This won't solve Sandy's problem though. Sandy, are your working conditions
> significantly drier than they used to be because of the season or location
> of your lab? There are several types of Mylar (polyester) but the material
> sold by Light Impression should be the one for conservation purposes
> without extra coatings.
>
> Luis Nadeau
> awef6t@mi.net
>
Luis,
When I coated on Mylar a couple of years ago it was during the summer
and the humidity in my lab was a bit higher than it is right now. However,
with the recent failed coating the humidity was not particulary low,
certainly no lower than 55%. I use both glycerine and sugar in my
pigmented/gelatin solution and was wondering if perhaps the former might
not contribute to the problem. I may have also caused the
problem by leaving the coated tissues on drying racks for several
days before putting them away.
In terms of Mylar itself, are there some varieties which are coated?
Sandy King
Sanking@hubcap.clemson.edu
>
>