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Why pot life is important when choosing a PU wood coating

What is pot life?

‘Pot Life’ is a term used to describe the usable life, or working time of two-pack coatings, such as epoxies or polyurethane (PU) coatings, which cure through a chemical reaction. It refers to the time from mixing the base component and hardener component, until when the mixed paint is no longer usable.

What happens if the pot life is exceeded?

It’s important not to use the coating after the pot life has expired, as although it may look fine initially, when the coating is cured, the bond and overall finish will be affected.

An expired pot life can cause various issues such as delamination of the coating due to inadequate chemical bond between the coating and substrate. The finish may appear gritty due to grains of polymerised material within the mixed material. The mixed material may have increased viscosity, resulting in poor flow-out and gloss. Additionally, the coating may exhibit poor chemical resistance and subsequent coatings may be prone to frying or wrinkling, especially if the coating is a primer or intermediate.

Once left-over mixture has reached its pot life, the best thing to do is dispose of it responsibly. Do not attempt to thin, refrigerate or add more of either base or catalyst to the mix in an effort to continue using an expired coating.

What are the benefits of a longer pot life?

There are several things that can affect the pot life, including the temperature the pots are stored at and the volume used, but perhaps most significantly is the specific hardener and base component used. PU wood coatings with a longer pot life can:

Reduce waste

With a longer pot life there is less wastage. The coating remains usable for longer, without impacting the quality, so there is less overall waste to dispose of.

Limit costs

When you are talking about wastage with a solvent product, there are two things to consider. Firstly, the cost of the product waste itself, and secondly the cost to safely dispose of hazardous solvent product waste. A longer pot life will reduce the cost implications of both.

Save time

With a longer pot life you can mix up the paint for the whole day, or you can do a whole tin at a time. This saves time as there is no stopping and starting, it works especially well if you are using an automated spray line.

Longer pot life with the Hesse Range

As a general rule, the majority of PU paints have a shorter pot life than AC paints – that is, until you discover the Hesse range which has longer pot life than most other PU ranges.

The Hesse range drastically reduces waste due to long pot life and has a high solids content which reduces the quantity used and application times.

For PU coatings with a long pot life, contact our expert team on 023 9223 3310 or email