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Forced Curing of Wood Coatings

7. May 2020 10:15

We are really excited about the IWF 2020 Holistic Approach to Finishing Symposium.

By: Joe Baggett, Innovative Wood Process Solutions

It goes without saying that coatings perform best and achieve their peak performance when they are properly cured. Whether it's a cabinet, furniture item, panel or other products, if they are packaged and put in the field with improperly cured coatings, they are susceptible to moisture, chemical, scratch and mar damage.

Finish or coating failure many times is the result of improperly cured coatings. This is avoided, in traditional, non-UV coatings, by making sure your curing process is delivering something called "forced curing." You have probably heard the term, but it is often one of the most misunderstood parts of the wood finishing process. 

Forced curing is a function of the chemistry of the coating, and the interaction with the wood surface, and relies on reaching a target temperature – a dynamic interaction between the temperature of the wood surface and that of the coating being applied. 

Basic thermodynamics for curing wood coatings

Curing technology actually starts with the board surface temperature, before the coating is even applied. Then it must account for the temperature of the liquid coating as it is applied. The first curing step of the coating after it is applied depends on the solids content, resin, binders, and solvents that make up the coatings. Evacuation of solvent through forced air and heat in combination is the first step after the coating has been allowed to flow out.

Then depending on the chemistry, raising the board surface temperature to the optimum level in the optimal amount of time is the goal. This is where we see many times that the target board surface temperature – the point at which we reach cross-linking, snap curing, polymerization, and other critical chemical reactions – isn’t achieved. For UV coatings getting the solvent out to where the UV light can properly cerate monomer dispersion is critical. 

 

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