RE: Humidity study - Reply

From: Scott Ostrem (
Date: Fri Jun 18 1999 - 15:38:49 EEST


Two years ago I got my hands on a paper titled, "Effect of Humidity on
the Properties of Steriolithography Parts Manufactured from SL5180 Epoxy
Resin". The paper was published by David Ian Wimpenny from the University
of Warwick. The paper includes a couple graphs that plot tensile strength
versus storage period versus humidity level. This paper is not electronic,
but if you provide me your fax number I would be happy to fax the paper
to you.

Scott Ostrem
The Boeing Company
St. Louis, MO

>>> <> 06/17 12:52 pm >>>

There has been a lot of study done on the topic and as soon as I can dig
the printed reports I'd be more then happy to send you a copy.

We have been using SL5180 in our machines for some time (one machine we
just acquired) and have seen QuickCast patters swell as much as 0.100".
real key is to prevent the moisture from getting to the part before you
cure it!. We started to cure all of our patterns in plastic bags with
SilcaGel packs to give the pattern the best shot at curing dry. Also we
have learned (the hard way, several thousand $$ thrown in the trash) that
QuickCast patterns should NOT sit around for more then a couple of days
any type of humidity! We have not had any swelling of solid builds,
although we normally don't track these as we do the QuickCast.

Hope this helps and send me your mailing address so I can send a copy of
studies that I do have.

Karl Denton
Senior Engineer
Williams International

        -----Original Message-----
        From: Alta Precision []
        Sent: Thursday, June 17, 1999 5:07 PM
        Subject: Humidity study

        Good day all,
        Has anyone out there done any in-depth studies on how humidity
affects SLA patterns, more specifically on SL5180 resin. We all know that
the parts tend to swell when exposed to high levels of humidity, but does
anyone have hard data that they are willing to share? I'll even listen
your worst horror stories. Thanks in advance.
        Bill Bernardo
        Alta Precision Prototypes
        Montreal, Qc., Canada <>

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