Homebrew PCBs

Hi Stefan,

Thanks for finding the MSDS for the "paper gum" glue I used:

.
http://www.chemquest.com.au/cgi-bin/cq_add_msds.pl?action=showMSDS&productName=CRAFTSMART%20PAPER%20GUM

The search function there does not seem to be working at present.  A
link on that page leads to the ingredients:

.
http://www.chemquest.com.au/cgi-bin/cq_add_msds.pl?action=showMSDSIngredients&productName=CRAFTSMART%20PAPER%20GUM

This states "Poly Vinyl Alcohol 10-15%" with a small proportion of a
biocide, to stop it going mouldy.  I guess the rest is water.

PVOH means, I think, Poly Vinyl Alcohol which can also be known as PVA,
but which is different from Poly Vinyl Acetate.

> Apparently this is a PVA glue after all. Does it smell right?

It is not an emulsion, like milky-white wood glue which I understand is
a water emulsion of some hydrocarbon solvent with Poly Vinyl Acetate in
that solvent.  It is a clear, free-flowing, but viscous, uncoloured
fluid.  I cannot detect any smell.

I dribbled some on a piece of glass and put it in the gas oven for 20
minutes or so at 200C.  What remained was about 20% of the volume, and
was clear and slightly brown.  It is hard and stuck firmly to the glass!

What remained softened with water.  Perhaps it would dissolve in water too.

This does not look like any kind of starch.  I assumed it was starch so
I tried it.  It seems Poly Vinyl Acetate:

.  http://en.wikipedia.org/wiki/Polyvinyl_alcohol

melts at 230C, but this would depend on its molecular weight.  The
boiling point is quoted as 228C, which makes no sense to me.

This melting temperature is, I assume, above that of laser printer fuser
rollers, so it will probably work OK.

Here is a page describing Poly Vinyl Acetate as a glue for bookbinding,
as a 20% solution in water:

.  http://cool.conservation-us.org/byauth/woods/pva.html

once cooled, it is a stiff jelly.  This doesn't match the glue I have here.

  - Robin