Heat resistant silicone

[Bruce Hall]

I would very much like your opinions please, about a product called Silirub HT N, a high-temperature resistant silicone sealant, and also to know if in principle it would be suitable for the following application. The product is sold by AB Sealants and is described at

have had 10 swivelling halogen spotlights fitted in the kitchen ceiling of my bungalow. Unfortunately, this has created significant airways to and from my loft above. As I never use the swivel function (the lamps are always in the =93straight ahead=94 position) I would like to seal the 3mm gap between the lamp-holder and the unit, to stop draughts and heat loss into the loft. The 50w 12v halogen spotlight bulbs generate a good deal of heat, so I am looking for a silicone sealant which will withstand it. There is plenty of ventilation into the loft from the back of the unit to allow for heat dissipation. I have approached the lamp manufacturer who can see no problem with my proposal, apart from possible invalidation of the guarantee, which has expired anyway. But what do you learned guys think?

Thank you

Bruce

[Spamlet]

Thank you

Bruce

I noticed they were selling silicone rubber bendy spatulas and glazing brushes, for use in frying pans etc, in Tesco the other day. Seem to recall they were being rated to about 240C, which I thought pretty impressive if true. Wasn't fooled into buying though. I'm holding out for a stainless steel glazing brush, if there is such a thing.

S

[Grunff]

How about the best of both - a stainless steel one with silicone bristles?

[Grunff]

Bruce, even standard RTV silicone is good for 250C, so it will be absolutely fine in this application.

The only thing I'd mention is that unless you leave the silicone to cure a long time (like a couple of weeks), you are likely to get some fumes when you first fire up. You can minimise this by using the thinnest bead you can, and leaving for as long as possible before switching on (at least 48 hours).

[Spamlet]

Ah, that looks better than the Tesco one, which was one of those silly things with a hollow 'stainless' handle that fills up with rusty water in double quick time. The silicone was very floppy too.

What I want is a wooden one with stainless bristles (so as for example, I can treat my boots with melted wax without melting/burning the bristles too... amongst other things.

Cheers for the tip anyway.

S

[Andy Dee]

I have had 10 swivelling halogen spotlights fitted in the kitchen

Rather than seal them as you suggest, why not fit fire hoods above each fitting. The hood would then provide the draught-proofing. It would also have the added benefit of doing what it was intended to do. I.e preventing your loft catching fire! :-)

A

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Spamlet" saying something like:

Would a brass-bristle brush not do for that?

[Bruce Hall]

Andy,

Thanks for your suggestion. I'm a bit strapped for cash at the moment and this seemed to be a cost-effective solution to stop the draught and heat-loss for a tenner (the cost of a tube of silicone). One thing I'd like to ask is whether there is adequate ventilation inside the fire cap, bearing in mind that most of the heat is given off at the back (loft-side) rather than at the front. If the caps are vented, then the draught/heat-loss problem remains, doesn't it?

Are you able to recommend a particular make? I looked at Aico caps a while ago and they were very expensive.

Bruce