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Which Temperature CPES Should I use?

Read this if you are not sure which temperature CPES (Clear Penetrating Epoxy Sealer) is right for you.

What is the difference between Cold and Warm weather CPES?

The only difference between the two different temperature variations of Smiths Clear Penetrating Epoxy Sealer is the solvent blend used that carries the Epoxy resin into the wood. The choice of which temperature CPES to use depends upon the work being carried out and the temperature at which the work will be carried out. The resin that you are left with after the solvents have evaporated is identical.

warm temperature cpes clear penetrating epoxy sealer
warm formula CPES

Warm Weather CPES is the original Smiths Clear Penetrating Epoxy Sealer. It was designed in America in California, and favours the warm climate that they have.

cold formula temperature cpes clear penetrating epoxy sealer
cold formula CPES

Cold Weather CPES has a solvent blend that is designed to evaporate more quickly for use in colder climates. As an aside it has a more pleasant odour as well. It is sold in Scandinavia as Lignu, which is the very same product with a different label.

How do I choose which temperature CPES to use?

Q1) Are you treating rotten wood to consolidate and repair it?

Y – Use Cold Weather Formula CPES. The solvents will evaporate faster, and this will speed the job up. Solvent evaporation even with CW formula CPES can take many days if you are treating large sections of wood. My solvent evaporation time treating a 5″ * 6″ (12.5cm * 15cm) structural timber in my house was around a week using cold weather formula!

N – Continue to question 2

Q2) You are using CPES on relatively sound timber, either new or old. Now we come down to the climate. Let us look at the job that you need to do now. What temperature will it be when you are doing the job?

Above 25 degrees Centigrade – Use Warm Weather formula.

Below 10 degrees Centigrade – Use Cold Weather formula.

Between 10 and 25 degrees centigrade – Continue to question 3.

Q3) You can use either temperature CPES.

If you already have any one temperature CPES on the shelf, use that.

If not, buy the one that will be most useful to you for most of the year. In the UK and northern Europe that is almost certainly Cold Weather formula. If you live in Southern Europe you may want the warm weather formula.

Clear Penetrating Epoxy Sealer CPES working and curing times

Damn. I have the wrong temperature CPES (Clear penetrating epoxy sealer)

Well. it’s not the end of the world. I fyou don’t want to buy more you can use what you have.

If you are priming, and have CW formula in a hot environment. Work when it’s cold and the sun is down.

If you are concolidating rotten timber to cure some rotten wood, and have Warm Weather formula CPES. Speed up solvent evaporation by directing a fan (cold air is just fine) at the rotted wood

How do I keep CPES for use later in the year?

Smiths CPES really only degrades by solvent evaporation. As solvents evaporate the blend becomes less suitable for penetrating the timber. The 1.9 litre cans will keep for at least a year if stored in a temperature stable environment (to stop the cans breathing) such as a cellar with the caps tightly screwed back on.


Read our CPES FAQ page for more answers to common questions, or contact us if you are still unsure about which temperature CPES you require.

If you wish to read more about CPES and how you can use it, follow this link: Smiths CPES Clear Penetrating Epoxy Sealer.

Our Rotten Wood Repair Kits contain CPES and Fill-It filler at a discount.

Get some more great information from the inventors website, Smith and Co.