LR White™/Gold™ Resin Systems
A word of caution about the catalyst
Formulated L R White resin, with catalyst added, is an unstable system, and
an ageing or "shelf life clock" starts once catalyst is added and that shelf
life, even under refrigeration, at times is thought to be not more than 6
months.
The point of this explanation is not to confuse, but to (hopefully) save
someone from ruining their important samples.
When L. R. White resin is shipped by the manufacturer, London Resin Company,
to the end users, usually the catalyst has already been added and the
customer has about six months to use the system. But the resin need not be
shipped with the catalyst added and one might then ask, why would it ever be
added. Why not let the customer do the adding of the catalyst.
The simple answer is this: It is very difficult to get the catalyst to
properly mix with the resin, especially when mixed in small quantities, and
since the amount to be added must be quite precise, it is difficult to get
the correct amount added for reproducible performance. Therefore, it is
generally unadvisable for the customer to be expected to add the catalyst on
the spot in their own laboratories.
When L R White resin is purchased from SPI Supplies, it arrives from the
manufacturer uncatalyzed. Hence the "clock has not started ticking". The
resin is stored under refrigeration until the time of sale at which time,
using our own considerable experience and special mixing equipment and
protocols, the catalyst is added and the product made ready for shipment to
the customer wherever that customer might be in the world.
Because the resin, once catalyst is added is so heat sensitive (to ageing,
if not also curing by way of a self-polymerization), SPI Supplies ships
catalyzed L R White resin only via courier and via the use of a cold pack to
keep parcel essentially refrigerated for its journey to the customer.
Delivery is nearly always affected within 72 hours of shipment and the L R
White resin is still cold upon arrival because of the effectiveness of the
frozen gel pack that is shipped with the resin.
But because of the growing "global village" nature of the microscopy
community, there can be confusion as researchers more from laboratory, and
at least several times a year we encounter users who either:
a) received L R White from SPI Supplies, as described above, but they think
(incorrectly) that they have to add catalyst and then the resin is over
catalyzed and with obvious consequences or
b) someone who is familiar with the SPI method of shipment ends up with L R
White from some other source, not realizing that for that resin shipment,
catalyst must be added. And when that happens, the resin just does
not polymerize.
Our procedure is to always ship L R White resin with catalyst already added
so that it is in ready-to-use form by the end user. That procedure is used
worldwide, and over the years, that approach has saved SPI Supplies customers
from having ruined experiments and wasted efforts. Of course not all
distributors have the advantage of large volumes like SPI Supplies, and their
only alternative to supply their local markets is to let the customer do the
mixing. Since USA prices are almost always lower than prices outside the USA
anyhow, a customer of L R White resin should give hard thought as to whether
they want to use resin that has been professionally mixed by the experienced
workers at SPI Supplies or whether they want to take their chances doing
their own mixing. Even with the special courier (and cold pack) charges from
the USA, the final cost to the customer is seldom higher than it would be if
ordered locally. And the customer is spared with the inconvenience and
difficulty of adding the catalyst to the resin themselves.
The addition of the catalyst is not to be confused with the addition of the
accelerator. This is entirely different. The accelerator is used when a
low temperature cure is being used. The accelerator is not needed when
polymerization is done, for example at 60° C.
How can you determine if the L R White resin you have is already catalyzed?
Look for the SPI label and lot number. If the resin came from SPI Supplies,
or via one of our distributors, it will have an SPI label and SPI lot number.
From the lot number we can tell you exactly the date the resin was catalyzed
by SPI Supplies. If the resin bottle does not have an SPI Supplies label,
then it did not come from SPI Supplies and in that case, you are going to
have to trace back to the source of your bottle of resin and then back to
the distributor who sold it to you and find out from them whether it was
shipped catalyzed or uncatalyzed.
To Ask a Question or Make a Comment
To Place an Order or Request a Quote
Return to:
Thursday March 18, 2010
© Copyright 2000 - 2010. By Structure Probe, Inc.
Contacting SPI Supplies and Structure Probe, Inc.
All rights reserved.
All trademarks and trade names are the property of their respective owners.
Privacy Policy
Worldwide Distributors, Representatives, and Agents
