Bathroom waste - unsure of where to put sealant?

[richierich]

Hi,

I am new to the forum and wondered if anyone had any advice on how to seal my new bath trap to the bath.

I'm a keen DIY'er but have attended a few plumbing courses, but I have to admit I am scratching my head a bit on
where to put the sealant.

Its a Duravit bath and waste. There is a rubber ring that goes through the plug hole. I presume I put sealant in the rubber insert where the plastic waste pipe pushes in. Do I need to put sealant inbetween the rubber and the bath on the underside of the bath and also sealant under the rubber inside the bath?

Also is dow corning 785 sanitary sealant good enough to do the job?

Any help would be gratefully received.

Many thanks,

Rich

 

[MC_Bob]

Only use sealant if no gasket is present, sometimes on inside of bath, or if bad mating surfaces.
You'd want something like lsx, not a sanitary sealant.
You dont need to use it unless the above is true. It can often cause rubber seals to swell or even slip during compression and not seat properly.

 

[richierich]

Thanks for the reply MC Bob, it has answered both my questions. I will put the sealant to one side then and hope the rubber gasket does its job.

The LSX you mentioned, do you tend to use that on new compression joints as well? I have read so many conflicting stories on whether to use ptfe, compound paste or nothing on compression joints. I haven't used anything on my compression fittings and am hoping the olive does what it should do but I am yet to turn the water supply on.

I'm just interested in knowing your opinion as a more experienced plumber.

Thanks again,

Rich

 

[Plumbstar Tom]

I agree, most wastes come with a washer of some sort so use that and check for leaks. Some cheap suppliers put a very thick foam washer to be used on the inside and it makes the waste stand proud of the bath and causes pooling, in this instance I would use a sealant get bin the washer.

On compression joints there are many conflicting views, I have noticed a tread towards using loctite 55 which I have used and been impressed with. I always prefer to use a tape on a compression joint to be 100% (arguments do say that a properly done compression joint needs no tape or anything). Even if checking when the water is turned on it may pop later on if there is a pressure surge or similar.

 

[richierich]

Thanks for the advice Tom. I actually used loctite 55 on the joint to the radiators. Do you think I should undo the compression joints I have done under the bath and wrap some around to be on the safe side? Am I correct in thinking that you put it around the olive rather than the screw thread?
Thanks,
Rich

 

[MC_Bob]

I use a lubricant on compression joints. Purely to stop the brass binding and giving you the feeling its tight when its really not. Anything else isnt necessary. 28mm and bigger I tend to paste.

 

[richierich]

Thanks Bob, whats the best brand of lubricant?

 

[Best]

Paste all compression joints. They def require it.
Take a good look at compression joints that have very slight white corrosion marks on them or green on the copper pipe & you will find that fitting has not been pasted if you open it.
I do a lot of small maintenance work for people & therefore I see work that is not new & the joints I find either seized or clearly corroded have been fitted dry. Doesn't matter if it is quality or cheap brass fittings. Minute leaks take time to leak through & evaporate, - so you will not realise your work is not sealing fully.

 

[Best]

Thanks Bob, whats the best brand of lubricant?

Paste, believe it or not.

 

[kris]

I never put the rubber ring on the inside of bath i use silicone because it tends to make the grating stick up past the bath base and it can look silly,, underneath i just run a ring round whats there to seal, and dow corning is one of my favourites,

 

[kris]

Reason i use silicone is because some baths the fibre glass is so rough that the seals that come with the waste kits just dont cut it, so dont be afraid to use mans best friend, at least its more of a garauntee,

 

[Best]

Reason i use silicone is because some baths the fibre glass is so rough that the seals that come with the waste kits just dont cut it, so dont be afraid to use mans best friend, at least its more of a garauntee,

Same with me, - the bath would have to be perfect smooth uniform base & the waste washer would need to be nice quality to do without sealant. On baths with rough base (just about all of them) I would use a little sealant & often on both sides of washer. Silicone is a bit risky as it tends to be like an oily lubricant & washer can spread, but I have used it a lot.

 

[plumben]

I always silicon the top, and silicone both side of the washer, same with the overflow

 

[Whyme]

I use it cos that rubbish little brass part inside the plastic your supposed to tighten enough to seal will pull out or the plug grate will squish in..If it was a proper brass waste i'd trust the washer. if plastic no chance.

 

[morganb]

I always get rid of whatever foam/rubber washer goes in the top side and just use sanitary sealant. Underneath I use the washer and more silicone. Just be careful when tightening the rubber washer doesn't 'pinch' out because of the silicone.

 

[turbotorch]

Plumbers Mait is good stuff, can get a bit sticky in the summer tho!

 

[JCplumb]

I use Plumbers Mait on top and silicone underneath, had a few pass when just using the supplied washers.
As for compression fittings on copper, if it's new copper and olive I don't use anything, otherwise it's a few wraps of PTFE on the olive.