8/7/98

Hello Microscopy Friends,



Does anyone have a working recipe for Araldite 502?



Today I rec'd tissues, processed by another lab that followed a protocol that stated "infiltrate in Araldite".

They have the tissues in a single solution of Sigma A-3058, Araldite 502.



Any suggestions as how long to reinfiltrate in a complete recipe before embedding? ( sm. int. aprox.1mm thick)



Also, we have 10 yr+ Araldite unopened in the lab. Does this go bad after an extended shelf life??



Thanks as always...

Linda Fox

lfox1@wpo.it.luc.edu



Linda-

we currently use this recipe:

Araldite 502 15ml

Eponate 12 (or equivalent) 25ml

DDSA 55ml

DMP-30 (catalyst)(1.5%) 1.25ml



there are several mixtures (of varying hardness) in print, check any Hayat

or Glauert book on basic principals in EM.

as for reagents that are 10 years old (this stuff is cheap, your time is

not) buy new resins, plastics, DMP-30, etc.

-Mike



MIKE ROCK

merock@du.edu

A couple of days ago I suggested DMP-30 as the epoxy component that is most

likely to go bad with long storage, but I didn't explain why. DMP-30 is

inactivated by water, and it WILL hydrate if it isn't stored carefully.

BDMA is an equally efficient accelerator, and is much less viscous than

DMP-30;it can and should be used instead of DMP-30 in ANY epoxy recipe

(Glauert, A.M. Accelerators for epoxy resins. Proc. R.M.S. 22:264,1987).

The persistence of DMP-30 is a historical accident.



Caroline Schooley

Educational Outreach Coordinator

Microscopy Society of America

Box 117, 45301 Caspar Point Road

Caspar, CA 95420

Phone/FAX (707)964-9460

Project MICRO: http://www.MSA.microscopy.com/ProjectMICRO/Books.html

Intertidal invertebrates: http://www.fortbragg.k12.ca.us/AG/PCI/pci.html



Linda

We have been using this resin in the research lab and up in the path EM

lab for over 15 years. Their formulation was based on Luft's work I

believe. It is one of the most viscus resins so we take a long time

infiltrating. Our last dehydration / dealcoholization step is propylene

oxide "PO" (yeah I know it's toxic) 3x 10 min. we then replace with a

50/50 mix of complete "comp" resin and PO The initial resin mix is; (27 ml

502, 23 ml DDSA. if you warm the bottles to 40-50 degrees C it stirs

easier). From this mix an aliquot is poured out and a 0.2%volume of

DMP-30 is mixed in. We call this "comp". (Some people substitute BDMA

for the DMP30 but I didn't see an infiltration or cutting advantage and you

sue twice the amount as DMP30.) This 50/50 mix is left capped over

night. The next day we replace the 50/50 with 100% fresh comp for

two hours, then embed into gelatin capsules or flat molds. The 100%

infiltration and embedding resin should be made up that day not the

previous days resin (it can be stored in the fig. and used for 50/50 the

next time, if that is not too long, say a couple weeks.)



In regards to OLD DMP-30.......they use it up pretty fast but buy it volume

so the last bottle is probably a year old. It is an anhydrous chemical and

the suppliers suggest a 3 month shelf life but obviously it can be

extended. I guess like some of the other topics we discuss ie stain and

fixative life its how much work vs precision, and whether you can redo

a grid or experiment. We're good but usually not picky, if in doubt order

fresh stuff its cheap. Lately I have switched over to the epon 812

group of resins, as they are much less viscus and cut just as well.

Good luck with your work.



Rick Vaughn

RLVAUGHN@MAIL.UNMC.EDU

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