replacing silicone beading - black mould thoughts?

[jkn]

Hi all I'm planning on replacing the silicone sealant beading around the bath and other parts of the bathroom. Mainly this is because the bath has shifted a little, and the original didn't use enough sealant IMO.

The bathroom has some of the dreaded black mould, including around the bath. Dealing with the black mould in general is not my top priority at the moment, but I don't want to make things worse for myself in future.

Would it be vital/important to clear out all traces of the old mould before re-sealing - ie. is it likely that current mould could somehow grow through my new sealant - or should I worry more about the mould re-growing on the new sealant? I plan on scraping out the old sealant as much as practical, and cleaning with meths.

Thanks for your thoughts.

Jon N

[meow2222]

youve got to remove all the mould, as putting sealant on top of mould means it isnt stuck, and thus wont survive.

There are mould resistant silicones, I'd use one of those, though I've not had long enough to know how effective they are.

A regular wipe with bleach kills mould. Also a quick wipe to remove the bulk of the surface water after use makes a big difference. Failing to dry out is what causes mould to get a hold.

NT

[Harry Bloomfield]

jkn was thinking very hard :

Easier, neater and with more mould resistance is the plastic stick on moulding you can get which comes in a roll. Centre line of the the moulding is hinged so it can fold tightly into the corner to seal against bath and tiles.

Both surfaces need to be scrupulously clean before you start and a wallpaper roller is needed to be able to apply the proper pressure to get it to stick fully to both surfaces. Don't skimp on this last point, or it will come unstuck.

[Peter Johnson]

Improvement in ventilation during/after showering/bathing will go a god way towards reducing mould if it doesn't eliminate it completely.

[Phil L]

I have, they're not.

if you have silicone it will get mouldy sooner or later, which is why I always reccomend using the rigid plastic 'L' strip that goes behind the tiles and has a flexible white rubber lip which laps onto the bath's edge...people say they're ugly etc, but they don't mould and we've had one on for almost 18 years and it still works, hasn't discoloured, never moulded up and has never needed removing with a blade and renewed every 18 months.

I understand however that this isn't feasible on existing tiled walls, but I thought I'd mention it to the froup for posterity.

[Martin]

I agree about the plastic strips.

You can get mould killer in a spray bottle for around £3.50 in places like Wilkinsons. Might be worth scrupulously cleaning off all mould and then using this stuff before putting the new mould-resistant silicone on. I read that bleach not only does not kill mould (my experience) but that it goes on to encourage it. Not sure I'd agree with that, but my experience is that the bleach appeared to kill it but it then did come back just as strong as before - maybe because it doesn't kill it and the cleaning merely helped spread the spores. I was told by a retailer of silicone that spreading silicone with the finger is the biggest culprit for putting mould in and that if you must use the finger, wet it only with washing-up liquid. I cannot vouch for this advice at all and I'm not sure how valid it is but it does make think of possibly using a surgical glove to spread the stuff rather than a bare finger.

I can vouch for the efficacy of the mould-killer spray but at the end of the day, it is indeed lack of ventilation that causes the conditions for the mould to grow in.

Food for thought I hope.

Martin

[Harry Bloomfield]

Phil L laid this down on his screen :

True, but the L shaped plastic strip I mentioned below does work well with a finished wall.

[jkn]

Hi Nigel (?)

Fair point. I wasn't referring to re-sealing over inches of the mould stuff, just wnering if there were (ahem) spore-adic small patches that I'd missed, whether it would make much difference.

Yep, I plan to, thanks.

Yeah, I know. Inadequate training of younger shower users is what it really comes down to. I'm just not following this one down at the moment for other reasons....

I see other people are recommending various strips etc. I've nvever been to impressed with the versions I seen of these, however I'm willing to learn. Why would these not be mould traps under similar environmental conditions?

Thanks Jon N

[Phil L]

I think you mean the adhesive variety? - mines not adhesive, it sits on the edge of the bath prior to tiling, it doesn't need fixing in with anything - the tiles and tile adhesive stop it from moving about and water can't get through it due to it being up behind the tiles by about 40mm, only the lip which is about 6mm is visible after tiling.

[Harry Bloomfield]

Phil L explained :

I did. The have a strip of thick sticky gunge on both edges and they form a good seal if th area is clean and you put plenty of pressure on, hence the suggestion of the wallpaper edging roller.

[The Medway Handyman]

I've used that a lot and its very good indeed. I've only ever seen it in B&Q as an own label product.

Too true!

Getting rid of the mould is important - use one of the activated bleach mold & mildew removers from the supermarket.

[jkn]

Hi Chaps

The Medway Handyman wrote: [...]

OK, I'm going to give this stuff from B&Q a go. Don't you love it when the package length (1.8m) is cunningly designed to not be long enough for the average use, grr...

Anyway, since the instructions are fairly paltry, a couple of questions:

- After folding, there is a 'short' and a 'long' side to the strip. I'm assuming you mount the 'long' side vertically (onto the tiles), the 'short' side horizontally (onto the bath). Yes?

- What do you do at corners? Stretch it round, mitre it, or something else?

Thanks, and a Happy New Year to all. uk.d-i-y is definitely one of the best Usenet groups out there...

Cheers Jon N

[Harry Bloomfield]

on 01/01/2007, jkn supposed :

Dunno, that we used was equal sided.

It needs to be carefully mitred before you take the backing off. It also needs to be made from two pieces - rather than one with a mitre notched out, or at least I found it difficult to stop the corner trying to straighten itself out if I tried it with one piece.

Work it outwards, starting from the corner for each piece and try not to stretch it as you apply it - stretching tends to cause it to reopen up the ends once in place. Easy way to hold it and stop it sticking on everything around you is to hold it folded flat, sticky side out -but not remove the backing more than needed for the immediate bit. Lay it in place gently, then use the flat edge of a bit of scrap wood to push into a proper 90 deg angle between wall and bath. Work it a bit at a time until you get it right, then put a little pressure on it to get it to stay put. Finally when it all looks right, run over it with the roller several times on each edge, increasing the pressure with each pass. You just cannot get the pressure needed for a permanent stick, without the roller.

If you are going over tiles, make sure the joints are flush finished - no gaps to allow water down them. Work with the bathroom completely dry and warm.

[Dave]

If it's the same thing that I am about to use, then Polycell do an adhesive seal that is 3.35 M long. It has equal sides as well. I think it comes in 3 widths, but I am not too sure if there are more.

Dave