Organic Solvent Based treatments are usually applied using low pressure (double vacuum) treatment plants & envelope treatment systems. The end product can be suitable for Use Class 1, 2 & 3 depending on the specifics of the process used.
Organic Solvent treatment is often used for joinery products as it does not change the dimensions of the time, or raise the grain. It also does not change the colour of the timber, unless it is purposefully changed for identification purposes.
Please see table below of how Use Classes are defined: –