ok to use Araldite Rapid on 500W quartz bulb?

[Lurch]

On Tue, 23 Nov 2004 20:41:54 -0000, "r.p.mcmurphy" strung together this:

You've obviously got some missing posts then, I can see another that answers the question quite clearly here.

[r.p.mcmurphy]

Oh well. but it seems that so many just want to make comment rather than answer questions sometimes!

Steve

[N. Thornton]

ok :) araldite still wont stand a chance, need something high temp. car accessory places might have something.

NT

[Andy Wade]

The smallest purchasable quantity of a suitable adhesive will probably cost at least ten times as much as a new lamp.

[Ian Stirling]

There are many high temp ceramic adhesives. Fire cement might well work. You'd need to bake in the oven at 250C to set it.

[Grunff]

That's if there was a suitable adhesive, which there isn't.

[Grunff]

IME fire cement isn't very adhesive. It has good cohesion, and will stay in place forming a pretty good seal, but its adhesion to other materials isn't great.

[Joshua Halpern]

You are showing your age. Glyptal went out about 1970. The two sealants of choice are Torr-Seal (Varian) or equivalent, an epoxy which goes to 10^-9 Torr and ~ 120 C, or silicone based resins that you can use (with luck) to 450 C The former have structural strength. The latter are strictly paint on and the replacements for glyptal (I remember glyptol, but that could be age).

josh halpern

[Tomasso makes things up]

The silicone one is the one I remember.

For reasons that REALLY make no sense to me now, I had to thermally decompose sodium azide (NaN3) under high vacuum...

Even in those days I was a theoretician, but for some reason got tied up in this weird system (optical pumping Na Zeeman hyperfine

- primitive, but was able to vary a lot of conditions).=20

I may be showing my age, too.

Tomasso.

[N. Thornton]

IME fire cement has more or less no adhesion at all, it merely sits in place, and is very weak. Its one and only good point is that it can cope with high temps, it really seems to have nothing else good about it.

High temp silicone may work, it can do upto 300C, and halogen capsules run at around 250C. But a new bulb is cheaper.

NT

[Paul]

JAAMOI, are Standard and Rapid of similar strengths at, say, -5C to

40C? I've often wondered, and used standard where strength is an issue, 'just in case'.

Regards,

Paul.

[Ron Jones]

Personally, I've usually found the Standard is better - so long as you can properly secure the mend for the full setting time of 3 days!!

[Tomasso sometimes makes things]

"N. Thornton" wrote=20

I went to a car accessory place and found an epoxy + iron "muffler = putty" product. It bonds to almost everything and has a continuous working=20 termperature of 260 C.=20

It was $14 for maybe 100 gm. To repair the ceramic part of the quartz bulb, I expect this would be fine. To repair quartz, no way!

Tomasso.

[Andrew Gabriel]

As it happens, the max working temperature of the pinch seal is

250C in a halogen lamp. Besides obvious things like overrunning the lamp or lack of ventilation, something which does sometimes result in their failure is overheating the pinch seal caused by bad lampholder contact generating heat. (That could also be the cause of the ceramic end cap breaking.)

Another issue with glueing such things is differential expansion as they change temperature. This can cause fine cracks in glass/ quartz/cintered aluminium oxide, which lets the fill gas out and air in. A high pressure halogen lamp which has such a crack and has filled with air whilst cold will often explode at switch-on. If it cracks whilst hot, the halogen will escape and the filament will more quickly evaporate and condense on the inside of the tube.

[Scrim]

I thought the 'pinch seal' was the little bobble in the middle where they seal it off after gas filling, rather than the end seals?

Scrim

[Zak]

I pay £3.99 for a new bulb from my local shop. I am sure I could get it for less elsewhere but then I would need to add the travel cost so I just say they are £3.99.