Framing to hang in a bathroom

[Roboframer]

Silicone sealant isn't that icky and if you're handy with the gun it can be done very neatly, anyway, it's inside the lip of the frame.

, the most likely catastrophe is moisture condensing on the glass

Which is why acrylic would be better.

[prospero]

Which is why acrylic would be better.

Depends on how steamy you get I suppose.

[Not your average framer]

I'm not a big fan of silicone, but if you need to use it, there are relatively neat and tidy ways to apply it and it's not rocket science to do this. Masking tape can be used to prevent silicone getting where you don't want it. After applying the silicone and smoothing the silicone with you finger any surplus silicone will be displaced onto the masking tape, which can then be removed to gether with the unwanted surplus silicone.

Getting all traces of silicone from your fingers can be more difficult, but silicone takes quite a while to set, so you've got plenty of time to get it off your fingers before handling the glass. I would suggest using a latex glove while smoothing out the silicone, followed by a clean latex glove for removing the tape. Although this sounds like a foolproof proceedure, it can still go wrong, as I have as times discovered for myself.

I seal pictures for bathrooms using the Linco aluminium barrier tape and 4mm Correx, but the weakess link at the end of the day is the self adhesive on the tape and the fact that dramatic changes of temperature over an extended period of time usually have some level of effect upon the service life of most self adhesive materials. Suppliers data sheets are generally vague about this and usually with good reason.

As an ex design engineer, this is one of the problem areas that you learn about with self adhesive products in general and as a result it is something to consider when talking to the customer. Silicone does not have the same problems, but there is still the out gassing of acetic acid, so maybe there is no perfect solution to this particuler problem.

[Roboframer]

Are we talking about the same stuff Mark?

I'm talking about silicone sealant, like wot you seal baths etc to the wall with - not the nasty smelling silicone adhesive. Outgassing isn't an issue whichever you use anyway - it wouldn't be inside the frame, it would be between the frame lip and the glass.

The silicone sealant guns are a bit cumbersome for such work but you can buy smaller tubes with special nozzles which are perfect for it.

[Not your average framer]

Yes, we are talking about the same stuff! The less expensive silicone sealers release acetic acid as part of the curing process and generally for a long time afterwards, while the more expensive silicone sealers which are used mostly in industry and not usually available in retail shops, release ethanol (alcohol) duing curing.

The electronics industry uses the more expensive variety for sealing high voltage assemblies, because the acetic acid released by the other variety slowly eats through copper conductors, causing the eventual failure of these assemblies.

As far as I know, there have only ever been these two varieties of R.T.V. silicone sealers. Most tubes or cartridges of silicone sealers are R.T.V. sealers. R.T.V. stands for "Room temperature vulcanising" The silicone adhesive you refer to is as you say quite a different product, usually known as silicone rubber adhesive, which is produced for industry in many different formulations.

Finally, there are also polyurethane polymers which contain silicone, neoprene polymers which contain silicone and vinyl polymers which also contain silicone. These types of polymers are generally produced as elastomers for "O" rings, pressure seals, flexible pipes and gaskets. Silicone based sealants, adhesives and related polymers are of enormous importance in the manufacturing of many modern high tech products.

[Roboframer]

OK, all I can say is I sell the 'clear' silicone adhesive and it stinks but the white bathroom silicone sealant doesn't, so I can't see how they are the same.

There will be other types of sealant you could use for sealing the glazing (back and front) anyway; it doesn't really matter what it is, it's not part of the frame innards, superglue, no more nails, epoxy resin - etc - would probably all be fine!

Silicone could be the adhesive stuff which does not come in the same containers as the sealant stuff, so you can't use a gun with it - or it could be the white sealant stuff, both will work but one smells worse and (as far as I know) only comes in toothpaste-type tubes - IOW there is no applicator you can use.

[Not your average framer]

Hi John,

Thank's a good question! I can't smell the two products you are using at your end, so the best I can do from this end is to offer a bit of guess work and hope that this will be of some help. I would expect the silicone rubber adhesive to smell more than either types of the silicone sealer. Also I would expect the acetic acid curing version to have a more noticable odour, than the alcohol curing version.

In both cases, either the acetic acid, or the alcohol has been added to prevent the silicone from curing in the tube, or cartridge.

Dow Corning used to have a good book all about different silicone products which explains things very well, but from what I remember about reading it, then may have been 20 to 30 years ago, I'm guessing that there may be some good info on their website, or at least that should be a good first place to start looking.