Use of jointing paste and PTFE

21 Nov 2007
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United Kingdom
Hi I wonder if someone could offer me some advice.

Some years ago before retirement I worked on a large Local Authority new build housing project.

The plumbing was all carried out in compression fittings and all the compression joints were made using Boss white (or some such other jointing compound) I asked the plumber about this and he told me that he wouldn’t normally use jointing paste with compression fittings but on this site the specification called for it.

I have heard arguments both for and against this practice and I wondered if there was now some definitive recognised consensus on the matter.

The reason I am asking is because I am starting a small modification to my system at home (nothing else to do now you see) and I would like to use the recommended method.

Also on a similar but not identical track is it recommended to use PTFE when making a joint between male and female ½” BSP as in tap connectors.

Again I have heard arguments both for and against, the main ones being that the joint is made solely by the fibre washer and not the threads so PTFE should not be used, but on the other hand, using PTFE on the male threads will “iron out” any discrepancies and prevent leaks.

I feel that, if there was no detrimental effect using the boss white and the PTFE, not being a plumber, I would tend to go for it to be on the safe side.

Your advice would be most appreciated,


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Belt and Braces Tony

Its less likely to leak with than without.

Never use ptfe and jointing compound together
Hi doitall

Thank you for your rapid reply which got right to the point-hardly had time to put my pen down.

You have confimed my very thoughts on this and I will use the jointing paste and PTFE (except not together)as you advise.

Thank you again for your help and interest, (but i have no excuse for delaying the job now).

Cheers and regards,


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