# Vac Vac



## Giff (12 Jul 2009)

Can anyone tell me what Vac Vac treatment is. Can PAR redwood be treated and is this a good option for external gates. Thanks Giff


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## bjm (12 Jul 2009)

Vac-vac is simply a method of applying (organic) preservatives into wood; after sealing in a chamber a vacuum is pulled to remove air from the timber after which the preservative is introduced into the chamber and allowed to penetrate the wood. A second vacuum is then pulled to recover excess preservative - hence vac-vac!

Redwood can be treated but the preservative will only penetrate the sapwood; the heartwood is impermeable but luckily is naturally durable. As for it being suitable the simple answer is yes but the real necessity for any preservative treatment is where timber is likely to remain wet in service; the use of preservatives in timber that are wetted intermittently is unnecessary. It is poor design (eg joinery detail that retains rather than sheds water) that has led to the belief that all exterior timber requires preservative treatment. The (portion of the) posts that are in the ground would benefit from preservative but I would opt for a CCA-alternative there.

Brian


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## PAC1 (13 Jul 2009)

It is a long time since I have had any work vac-vac treated but from memory the joinery used to come back very wet because whilst it is treated under pressure it is not dried. Two points to consider are: 
1. Joints if you rely upon the glue make sure it is waterproof. It would be best to dowel peg the joints. 
2. On occasion I have seen joinery come back twisted. 

Having said that it is an effective process. 

You can buy timber pre treated but you need to be careful when carrying out the joinery to protect yourself from the treatment i.e. gloves.


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## Giff (13 Jul 2009)

Thanks for the advice Brian...what is CCA ? Thanks Giff


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