The fire retardant treatment of wood in an autoclave is a technical process, which can be divided into five large steps:

Step 1:  The preparation

During an initial inspection of the wood, we will check the quality and quantity. 

After this check, we will slatte the wood and organize it into blocks according to the weight and size of the planks, in order to optimize the autoclave process.

 After the division of the wood, we measure the weight of the parts we are going to autoclave in different steps.

Step 2: The autoclave treatment

After the preparation, the wood goes into the autoclave for a fire retardant treatment, with the fire retardant Burnstop IM-W475HP phosphates.

 A fire retardant autoclave treatment takes between for 30 minutes and 3 hours, with a pressure of 2 to 10 bar, depending on the type of wood.


Step 3: The first drying

After the autoclave treatment we take the wood to the drying rooms, where the temperature is gradually increased to 56°C. 

This gradual drying takes several days and it is important to achieve optimal fire resistance.

Step 4: Aftercare treatment

For outdoor applications, the treated wood receives a water-repellent aftercare treatment with the Pelicoat Pro Wood on all four sides. 

The Pelicoat Pro Wood is a water and oil repellent coating, which protects the fire retardant Burnstop IM-W475HP phosphates from external weather conditions. 

Step 5: Final drying

The wood is carefully placed on the racks to dry, before we finally stack it on pallets and the wood is ready for departure to the customer’s site.

All these steps are done on our site at Yepp NV, where we carry out the treatments from start to finish.

Do you have questions about autoclave treatments?