London Resin

LR White™ Resin System

This one step single component acrylic embedding resin system has many advantages, its ultra low viscosity, only 8 cps, is almost like that of water and will infiltrate just about any type of sample. Even large blocks impregnate surprisingly fast. Another feature is convenience since one can do both TEM and LM sectioning from the same block.

Polymerization is started either by heat or when the need to preserve the sample's antigenicity is paramount, then also by a low temperature UV cure. One characteristic of the cured block is that sections tend to be quite hydrophilic. Actually LR White is quite a versatile embedding resin and there are quite a few interesting applications that have been described. So far as resins go, LR White is pretty easy to use, and problems when they do arise, are encountered only very rarely.

Chemical etching of LR White sections:

This technique has been used to increase the accessibility of the antigenic sites, or "antigen retrieve" in the section for immuno electron microscopy. We would recommend the paper "Antigen Unmasking for Immuno electron Microscopy: Labeling is Improved by Treating with Sodium Ethoxide or Sodium Metaperiodate, then Heating on Retrieval Medium", Journal of Histochem. and Cytochem., 43:115-123 (1995).

Staining the sections:

There have been numerous reports in the published literature describing various staining techniques of immunolabeled sections. Most of them involve the use of uranyl acetate as a negative stain.

Embedding of Plant Tissue:

For many workers, there is experienced some difficulty embedding plant tissue with other embedding resin systems. LR White, with its viscosity that is like water, can be very easily infiltrated (relatively speaking, of course) and there has been quite a bit published on the embedding of plant tissue.

The resin itself comes ready to use and if intended for use at low temperature, one would need SPI #02648-AB, accelerator which comes in a convenient dropper bottle. Available in three grades, hard medium and soft, with hard and medium grades for most users being much more popular than the "soft".

L R White vs. Araldite® 502 Resin embedding

Despite the less rigorous processing associated with the use of LR White, neither the appearance or the amount of the extracellular material was affected by the different embedding protocols. We interpret this to mean that some antigenic sites are more sensitive to alcohol disruption than others, and in this case, the sites must have been quite resistant to such disruption. But for other systems, the opposite is true. The point is, for a new system, it is often times worth trying several different embedding approaches, in order to determine the one that is the most optimum for that specific situation.


All three resin grades can be polymerized either chemically, at low temperature using UV irradiation at 365 nm, or by elevated temperatures, either by conventional oven or microwave techniques. Note that this resin system is not compatible with the use of acetone, since the presence of any ketone will inhibit polymerization.

Each bottle of resin comes complete with five different monographs to provide assistance to the user of the resin:

An understated potential safety risk:

We are addressing now the cured block, something that to most people is about as inert of a material as one will find. But the standard practice in many laboratories is to use a small jeweler's (or even a small hack) saw to cut the block down to the right size, sometimes even to shape it. We want to address the dust that is generated and how its exposure can and should be minimized.


Individual components:

Size SPI #Each10+30+In Stock
Hard Grade 500 ml02645-AB$138.22$124.40$117.49 Add to cartYes
Medium Grade 500 ml02646-AB138.22124.40117.49 Add to cartYes
Soft Grade 500 ml02647-AB140.00126.00119.00 Add to cartNo
Accelerator(UN2810) division 6.1 OK SPI 10 ml02648-AB21.6019.4418.36 Add to cartYes

Note on shipping:

We strongly recommend that the LR White Resins be shipped in low temperature packaging and by the most rapid means possible. LR White accelerator may be shipped without low temperature packaging.

Storage conditions: All three grades of resin should be stored refrigerated at 4°C. Accelerator can be stored at room temperature.


LR Gold Resin

This acrylic resin facilitates the embedding of unfixed material at low temperatures, enabling high-quality histochemistry and immuno-cytochemistry of fixation-sensitive enzymes and epitopes. It is non-toxic and may be cured with visible light and reveals high-quality morphological details from 1-4 µm sections, providing a faster and lower-cost alternative to frozen sections.

LR Gold can be catalyzed in a number of different ways depending on the choice of catalyst (e.g. color of light to initiate polymerization, temperature, etc.). The resin was specifically formulated to be catalyzed with benzil and it will work very well with blue light and will also polymerize below 1° C, often times needed in order to enhance antigenic preservation for experiments in immunocytochemistry.

It can also be polymerized at sub-zero° C temperatures by the addition of benzoin methyl ether and polymerization with UV light. As this is intrinsically less safe than the blue light/benzil regime and offers no advantages in performance of the resin, this is not the method of choice for LR Gold. For polymerization at room temperature, this can be achieved readily via the addition of benzoyl peroxide. Such a polymerization is exothermic and rapid, with the total time needed for full polymerization on the order of ten minutes.

Click here for LR Gold Data Sheet

Individual components:

Size SPI #Each10+30+In Stock
LR Gold500gm02651-AB$159.18$143.26$135.30 Add to cartYes
Polyvinylpyrolodone (osmotic adjustor) 50gm02652-AB16.7915.1114.27 Add to cartYes
Benzil (activator) 50gm02653-AB16.9115.2214.37 Add to cartYes
Storage conditions: Room temperature