Re: glyoxal yellowing

From: Kees Brandenburg ^lt;ctb@zeelandnet.nl>
Date: 02/03/05-01:02:50 PM Z
Message-id: <1320915.1107457370448.JavaMail.swiki@G3.local>

>Kees, the Maco hardener---very interesting! Is the percentage of
>glut in it really 2.5-5%? If so, then 50 ml of this is a lot more
>than my 6 ml. per liter of gelatin.

Yes, it is a lot more then your 6 ml. In fact I reduced it a lot later and hardened also with 6 ml. Indeed I am sizing and hardening in two steps. I do tray sizing in big batches and continue sizing sometimes the next day. When mixing the hardening agent with the gelatin it doesn't keep.

I posted about the Maco geladur before on this list.

<http://www.usask.ca/lists/alt-photo-process/2004/feb04/0527.htm>.

The percentages are from the Maco Geladur safety sheet(somewhere on www.mahn.net, the english version is missing - but I have a pdf somewhere).

For gum printing the gelatin has to be hard enough to resist the abrasion from the coating,soaking, streching and drying. But there is always a difference between coating a first layer over the hardenend gelatin and the next layers of gum. The first layer is allway somewhat unwilling to smooth. Second and folowing coatings are much easier to egalise. I have the impression that too hard gelatin is moer difficult to coat. When I tried coating my first glut paper (yes the 50 ml one - fabriano uno - a first try unfortunately - not so clever when researching a new approach)it was very hard to coat. Overhardened?

Kees
Received on Thu Feb 3 13:03:05 2005

This archive was generated by hypermail 2.1.8 : 03/01/05-02:06:54 PM Z CST