Reverse crystallization of epoxy resin potting compounds with honey trick

Crystallization can occur in all epoxy resins. Crystallization is a change in the aggregate state, i.e. the change from a liquid state to a solid crystalline state.

Crystallization of epoxy resin can occur in various ways.

The following signs indicate crystallization:

• milky and foggy turbidity
• Free-floating crystals
• Crystallization in the form of “salt grains”
• Crystal masses
• Completely solidified mass

The crystals are heavier than the liquid resin, which is why the crystals sooner or later settle at the bottom of the container. These crystals also settle on the side walls of the respective container.

Most epoxy resins have a material that is solid at room temperature as their main component. When crystallization occurs in a liquid epoxy resin, this liquefied material basically returns to its original solid state.

The causes of epoxy resin crystallization include the following:

• extreme cold (- 40 °C)
• Temperature fluctuations
• High purity
• low viscosity
• High moisture content
• Impurities

The crystal growth of epoxy resins is similar to that of other materials. The crystallization process is normally triggered by a “crystallization nucleus” where crystal growth takes place.

Basically, crystallization of epoxy resins is nothing unusual. As these crystallizations cannot be completely controlled, they are difficult to avoid. It is therefore difficult to predict crystallization. There is no advance warning.

It may even be that only part of a particular batch is affected. Nevertheless, there are preventive measures that can be taken against crystallization of epoxy resins.

Since the crystallization of epoxy resin is based on the same process as the crystallization of honey and the reversal of the respective crystallization therefore also works in the same way, the latter is also referred to as the honey trick.

The honey trick, i.e. dissolving the crystals in the honey or epoxy resin, simply works by heating the respective substance to 65 °C. You can melt the crystals overnight at this temperature, for example. You can melt the crystals at this temperature overnight, for example. This is because it can take several hours for all the crystals to dissolve through heating, especially if the container is large.

However, it should normally be possible to reverse all crystallization by melting within 20 to 40 minutes. It is best to check the melting results after 10, 20, 30, 40, 50 and 60 minutes. As long as the epoxy resin has not yet been mixed with another material, there is no need to worry about the epoxy resin potting compound hardening as a result of heating.

It is important that all crystals are really dissolved, as otherwise unmelted crystals serve as “nuclei” that lead to new crystal growth. Once all the crystals have melted, the material should be allowed to cool to room temperature, after which it can be used normally. Without this cooling, the resin may flash harden.

However, heating alone is not enough. The resin should also be stirred when heating so that the heat is evenly distributed.

In addition, material on the sides and bottom of the respective container should be scraped off. In this way, you can ensure that all crystals are melted down.

One-component systems should not be heated. Otherwise the product may be damaged or harden.

Crystallization can be prevented by keeping spouts and container caps clean, for example. Using clean tools and equipment can also prevent the crystallization process caused by impurities.

Storing and transporting the epoxy resin at constant temperatures can also prevent crystallization, although you should ask the manufacturer or seller for the ideal storage and transport temperature of the epoxy resin in question.

In addition, the following measures are recommended to prevent delays due to crystallization in your own production processes:

• Testing the supplied epoxy resins for crystallization and heat treatment of the affected stock
• Correct storage of the epoxy resin as recommended in the data sheet, although crystallization is possible even when stored properly
• Testing of epoxy resins before use and heat treatment if crystallization is detected
• Training employees in the correct handling of epoxy resin and crystallization

If you are looking for an epoxy resin casting compound, you can find it in the abovo online store, where the products Loctite Stycast 2850 FT, Loctite Stycast 2850 MT and Loctite Stycast 2651MM are offered, among others.

Either the Henkel potting compoundselector or the abovo experts, who can be contacted by phone or e-mail, can help you choose the right potting compound.

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