It seems that we have to explain our gum solution problem once more. It has
nothing to do with sizing the papers or adding formaldehyde or not. Our
question is why the gum solution suddenly acts as been hardened. After more
than ten years experience with making our gum solution (yes, we prefer
making it from lumps and not from powder) we suddenly get a problem that we
had never ever met before! Trying to explain again (not in Swedish!!!)
We have one kilo of gum arabic, very good quality. We use approx 350 g and
make one liter at home, bring this liter to the course where it works very
good. This solution is finished during the course so we have to make more.
During the course the students sized papers for the gum prints. As the
students were very productive we had to make two big batches of papers.
Both times we hardened the papers with glyoxal and this was the first time
we used this stuff. Yes, there was some odour in the room and the students
complained a little (they have never used formaldehyde so they do not know
that it is worser...)
>From the same paper bag where we first took our gum lumps (at home) we now
took approx 350 g to make a new solution at the course. After a while -
when the lumps were almost dissolved and NO glyoxal was added the solution
turned very snotty! Could not explain why to the students as the same lumps
had worked at home.
When back at home we were comparing two suppliers and suddenly one solution
turned snotty. The lumps that turned snotty were from the same paper bag
that 1) worked good at home and 2) turned snotty after ten days in the
classroom where we had sized paper for gum printing.
Our question was - can gum lumps absorb glyoxal or "pre-harden", when
"glyoxal is in the air" - and why???? We still have some lumps in this
paper bag - shall we throw them away? As we are going to order about 20
kilos of gum lumps - can we order it from the supplier or not? We do not
believe that the supplier has something to do with this - we suspect that
it must be the glyoxal as it was the first time this happened and the first
time we used glyoxal, and the first time we stored gum lumps in the same
room as the papers are sized and hardened - but are we right or not?
Help, please
Hans & Chia