SC - Re: Egg Tempera OT

[RANDALL DIAMOND]

Maredudd  asks:
>>>>Media in period could be gum Arabic (or some 
other vegetable gum) or egg yolk - however I worry 
about egg yolk. What happens if that scroll gets
rained on? Not only would you smear the paints, 
but the possibility for spoilage seems high. Besides, 
I can't *stand* the smell of egg yolk, and I'm
not sure I could work with it on that basis.<<<<

Egg yolk is THE primary media for tempera throughout
the Middle Ages.  In the Renaissance, when the artists
were switching from wood panel to canvas, they also were
experimenting with many kinds of oils.  By the end of the 
SCA period, oil mediums had almost completely replaced
tempera in use.  Don't worry about rain smearing egg yolk
media tempera, the stuff polemerizes rather quickly in 
drying and becomes insoluable in water.  Have you 
ever had to to use steel wool scrubbers to get dried egg
yolk off a mixing bowl.  Same principle.   If you are worried
about spoilage (on the illumination I presume), don't.  It
is fundamentally changed to a very inert polymer and will not
spoil at all.

>>>>However, in the interest of gaining a bit more 
knowledge, does anyone have experience with egg 
tempera? What's the "shelf-life" of egg tempera - 
do you want to refrigerate it? How does it perform 
over the long-term life of a scroll? If you live in a 
humid climate, does it go all fuzzy after a hot,
wet summer under glass?<<<<

You don't mix up big batches of egg tempera when 
painting; you mix your tempera powders with fresh,
room temperature yolk as you are painting, thinning with
clean water to the desired transparency levels.  The 
beauty of properly applied egg yolk tempera is that
you can sketch out line forms and apply multiple layers
of transparent to semi-transparent colour over it without
redissolving the underlayers (assuming you let them dry
properly between applications).  What most folks think of 
tempera is the rather flat and dull grade school stuff
(pre acrylics).  Period tempera is almost radiant in its
colour subtlety.  You do not need to refrigerate as it is
best to work fresh every day.  Period temperas are 
just as wonderfuly fresh and bright as they were when
painted.  The substances in yolk make one our most 
durable art media.  Oils by comparison, do not hold up
anywhere near so well.   If you don't apply the tempera
to thickly, caking it on, it should hold up on scrolls quite
well.  The yolk is also a good bonding agent to the 
parchment.  If it was thoroughly dry, it is not going to 
get "fuzzy" under glass due to humid conditions.  You
are more likely to have spores attack the paper itself.

One of the other things to know is that the "tempera"
powder you get at stores is not necessarily period
in composition.  Period artists ground and compounded their
own from various substances for different colours.
I am not sure that all commercial (just add water type) 
powders will produce a satisfactory period appearance.
It is a process requiring quite a bit of study to get it
right.  You might be better off with watercolours, which
were also used quite extensively in the late Renaissance.

Incidentally, for the gold linework like halos and such, the 
slime from heating snails was used with a little egg yolk as 
a binder for powdered gold.  This was a different technique
than application of gold leaf in an area though.

Akim Yaroslavich
"No glory comes without pain"