[Jewelry making - Article 01067] - [Orchid] Investment mixing charts

[Karen Goeller]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========

Folks,

    In our lab at the college, we've always mixed investment by "feel" to
     teach students how to determine the appropriate consistency.
    Basically, our approach has been to use about 75% of the flask's
    volume of room-temp  water, then adding the investment and mixing
    until it's the consistency of yogurt/sour cream/pancake batter.
    Vacuum for 3 minutes, pour into flask  and vacuum flask another 3
    minutes.  The more experienced students can do  this in their sleep
    and know exactly the consistency to look for. 

    Needless to say, though, with beginners among us (and even some of
    the old-timers), there has been a decent amount of waste.  Since all
    of the students chip in to pay for the investment, it only seems fair
    to do  what we can to level the playing field and keep "beginner
    waste" under better control. 

    Hence the introduction this semester of "The Chart" - the official 
    mixing chart that comes with each batch of investment that tells you
    how many pounds of investment you need to how many mL of water for
    each size of flask.  We have a good (and new) investment scale and
    well-marked  graduated beakers.  The problem is that if you follow
    the chart, you get a very  THICK investment that sets up WAY too
    quickly.  It's the consistency of a very thick pancake batter when
    mixed and you can vacuum it for about 1.5  minutes at each step - at
    the most - before it sets up. We had some of the  most experienced
    students do their flasks this way and follow the chart so  that we
    could test it and see what the results were.

    SO. do any of you know any sources of GOOD and accurate investment 
    mixing charts?  I'm reluctant to spend the time it would take to
    thoroughly test and revise this one, but am tempted at this point to
    hide all but 3 or 4 flask sizes and work out the proportions for them
    and post them. However, if I can get a good chart, it would
    definitely help me avoid that step  and we could maintain our
    flexibility. 

Many thanks for any pointers!
Karen Goeller
kgoeller AT nolimitations.com
Hand-crafted artisan jewelry
http://www.nolimitations.com

____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________