RE: SLA-resin

From: Blasch, Larry (
Date: Fri Apr 12 2002 - 15:55:50 EEST

Dear Ola and list,

Although there is no way to reverse the polymerization that has occurred in
the vat, you can remove the solid and partially gelled resin by filtering it
out. This is a difficult thing in any SLA-250/190 machine, but it is
especially hard if you don't have an interchangeable vat.

My original SLA-250 had the swivel drain tube in the front of the tank. If
your 190 has the same, you can go to any commercial paint store or hardware
superstore and get a couple of 5 gallon buckets and 5 gallon "paint filter
bags". The paint filter is a large, fine mesh bag with an elastic band that
can be inserted into the 5 gallon bucket and the elastic holds it in place.

Before you start, make sure that you are prepared, wear the proper
protection and be careful.
Spilling 10 gallons of resin can make a real mess that may require a HAZ-MAT
team to clean up.

If you don't have long sleeve, gauntlet style gloves, you can put your
gloved hand into a large plastic bag to extend the protection all the way up
your arms. You will need this if you are reaching down to the bottom of the
tank to scrape out the "submarines" in there.

Drain your tank completely into the two buckets. This may take a long time
and the drain tube may get clogged with cured material. If it does, you can
raise the drain tube up and blow the material back into the tank to clear
it. Scrape the inside of the tank down with a putty knife or a kitchen
spatula to get the globs of gelled resin that have accumulated over time.
This is a messy job, but it will be worth it in the long run.

Now you can gather the filter bag and slowly raise it out of the bucket, I
suspend the filter bag from a hook to allow as much of the uncured resin to
seep out and be recovered. This may take you the entire day to complete, so
don't try to rush it. you will end up with a couple of filter bags with
balls of cured and gummy threads in them that you can cure and dispose of.

While you are at the paint shop, ask them if they can sell you a viscosity
cup, it is a simple and cheap item that you can use to determine the
thickness of your resin.

Good luck, It's a messy job... but somebody's got to do it.


Larry Blasch

Lawrence R. Blasch
Design Engineer
CAE Systems Administrator
OPW Fueling Components
P.O. Box 405003
Cincinnati, OH 45240-5003 USA
Voice: (513) 870-3356
Fax: (513) 870-3338

-----Original Message-----
From: Ola L.A. Harrysson []
Sent: Thursday, April 11, 2002 6:23 PM
To: Rp-Ml
Subject: SLA-resin

Dear List,

We have an SLA-190 with a vat full of old SL 5170. It is still working but
the material properties are not the same anymore and a skin is formed on the
surface of the vat during a build. Is there any way that you can recondition
the resin? Or is it just to empty the vat and send it for disposal? Any
ideas would be highly appreciated. Anybody have some SL5170 that they need
to get rid off???


Ola L.A. Harrysson, Ph.D.
Assistant Professor
Department of Industrial Engineering
North Carolina State University
Raleigh, NC 27695-7906
Phone: 919-513-0220
Fax: 919-515-1543

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