Experience since 2004

All timber is treated in strict accordance with British Standards BS8147. An environmentally-friendly solution CELCURE C4 also called Naturewood is used and contains NO chrome nor arsenic. It is produced in Sweden by Koppers – a company that has over 100 years experience in the protection of construction timbers all over the world.

Timber pressure treated with CELCURE C4 can be used for fencing, timber decking, landscaping, constructional and other types of timbers that need to be protected from decay fungi, insects and water. 

Naturewood products will initially have a green appearance that will with years weather and fade to greyish brown colour after long term exposure to the sun and other nature elements, without altering the protection itself.


What will be the lifetime?

To ensure longer lifetime timber products must be treated with wood protective preservative. The most efficient preservative that protects against the fungi causing rot is OSMOSE C4, which is used for the industrial vacuum pressure treatment. Pressure treated timber does not need an additional treatment and is ready for its initial use. CELCURE C4 treated timber will last 5 to 20 years even when in direct contact with ground or water. The vacuum pressure treatment is implemented in a special autoclave, where the following processes take place:
  • vacuum that opens the smallest pores of wood and absorbs the maximum moisture from the wood surface;
  • pressure (up to 12 bar) that presses the protective agent into the wood as deep as possible;
  • vacuum that absorbs the excessive moisture from the wood surface.

Spruce and Pine

Spruce and pine species differ considerably in relation to their structure; therefore the result of impregnation differs for these types of wood. The picture shows the difference between impregnation of pine and spruce.

We can see that pine, depending on the amount of humidity, can absorb the full dosage of protective agent – till the core. But the maximum of the impregnation of spruce, depending on on the moisture content is 2-5 mm deep. Therefore the lifetime of posts differ considerably.

priede un egle






Dried or Undried Posts

As it was mentioned before, the pine posts, dried up to 28% moisture content can absorb the protective agent fully – till the core.


But the undried spruce posts will absorb an insignificant part of the dosage. Dried spruce species can absorb the agent to a maximum depth of 5 mm. 








What is the difference in price?

Pine posts need to be dried in kilns and impregnated with treatment class 4 which requires 2 – 3 times more preservative than a standard class 3. Accordingly such product could cost for about 50% more comparing to a standard class 3 quality with mixed spruce/pine species.

Treatment classes

The result of impregnation may be influenced by different factors, for example, the wood species, humidity and the process of impregnation itself. Therefore there are several treatment classes. We use only class 3 and 4:

Class 1
For the use above the ground, in dry places under the roof. There is a risk of insects infestation.
Class 2
For the use above the ground, in dry places under the roof, but with the possible affect of moisture.
Class 3
For the use above the ground, in wet places without the roof (on the terraces). May be used in the ground which is not particularly wet.
Class 4
In the direct contact with water and in the particularly wet ground.

The posts stored at out warehouse mostly are of standard quality – undried and impregnated with treatment class 3. The lifetime of such posts, depending on the diameter and place of use, is 3-10 years. The thicker is the post and the dryer and sandier is the ground, the longer will be the lifetime. 

In order to ensure the lifetime up to 20 years, the posts used for pastures, fences, fastening of banks or other needs should be impregnated with treatment class 4. In order to perform the qualitative impregnation with treatment class 4, the following conditions should be observed:

  • the posts should be from the pine species;
  • the posts should be dried before the impregnation – moisture content should not exceed 28%;
  • during the impregnation the protective agent should be considerably pressed into until the core until it penetrates it at the full dosage.

Treatment process

Step 1

Prepared timber is loaded onto trolleys so that the working mixture for impregnating could be sprayed on the timber.

Step 2

Vacuuming is the first stage of impregnation process, the air is pumped from the autoclave, and both air and the excess moisture are pumped out from the pores of the timber’s top layer. Vacuuming mode is maintained for a certain time.

Step 3

Vacuuming is the first stage of impregnation process, the air is pumped from the autoclave, and both air and the excess moisture are pumped out from the pores of  timber top layer. Vacuuming mode is maintained for a certain time.

Step 4

The working mixture flows of its own accord from the reservoir under autoclave after the vacuuming mode is completed.

Step 5

After complete filling of the autoclave with the working mixture for impregnation the pressure mode with maximum pressure of 12 atms (bars) starts. The pressure maintaining conditions are kept for a specific time period (0.5 – 2 hours), depending on the particular class of treatment. The whole process is automized.

Step 6

After the the working pressure mode is completed the working mixture flows of its own accord to the storage reservoir for the impregnation, and after complete emptying of the autoclave the final vacuuming process starts and lasts for approximately 15-30 minutes. The process of the final vacuum provides pumping of excess fluid from the timber surface.