Common Coating Reactions

There are many reactions that can happen between a coating and timber. Below are a few of the common ones and what causes them to occur.

Blooming – possibly the most common, particularly in humid/wet months. Blooming occurs when the coating has been applied when there is too much moisture present in the air during the application/drying period. It causes the coating to have a milky appearance.

Although not aesthetically pleasing, it is not damaging to the performance of the coating. It will eventually go away, however this process can be very lengthy. A wipe over with a turps dampened rag may help speed up the process. It is not recommended to apply more coating over the top as this will make the drying out of the initial affected coating take longer.

Bubbling – another reaction caused by moisture. This one happens along the grain of the timber surface and appears as small bubbles. This happens when there is too much moisture in the timber at the time of application and is often seen most when in sunlight and the moisture is trying to escape. Most will settle. Bigger ones can be popped with a pin to let the moisture out. If they dry on the surface, the only method of removal is to lightly sand.

To avoid this reaction, it is important timber is given enough time to dry prior to initial application of the coating.

Alligatoring – when the coating you’re applying is not compatible with the coating that is currently on the surface. The coating starts to separate on the surface as you are applying it. It looks like an alligators back (hence the name!).

With Sikkens products, it will most commonly occur with the application of Supernatural over the top of HLSe when the HLSe coating has not been given enough time to dry. In this instance, keep brushing the product in and it will eventually take. Finish the board you are doing then stop to allow everything to dry thoroughly before proceeding.

The most common reactions occur as a result of too much moisture being present. It is really important to allow enough time for timber and coatings to dry thoroughly, and to be aware of the weather conditions you’ll be coating in.

Please refer to our TDS for more information on application conditions.