Refractory brick equivalents, but smaller and free.

If, like me, you have occasion to silver solder small parts from time to time you will either have a proper hearth or, like me, scrabble around to find something to prop the parts on and which won't matter if it gets spoiled/burnt/melted etc.

When we tore out a wall-mounted gas fire recently, out came four spiky backplates and several plain larger pieces of the same refractory material. It's designed to glow red in the heat of the gas flames and hence is well suited to use as a hearth lining. In practice I simply open up my bench vice to near maximum and rest one of the larger pieces across the jaws, thus protecting them. Other pieces, including broken bits, can be arranged to provide a nice heat reflective backdrop. The spiky bits are particularly good for supporting parts on just the points, allowing heat to reach underneath surfaces as well.

People are always dumping gas fires, so root around your neighbour's skip, (having asked permission first, naturally).

Excellent idea, Ken

... If you need something for very small items [with the very considerable advantage of having a grid of holes, useful for jigging], I recommend these.

MichaelG.

.

Note: I haven't counted them, but I suspect that "thousands" might be a slight exageration of the number of holes.

any UK builders merchants can supply the current equivalent of thermalite blocks (breeze block size) for a few quid each, which i use for my brazing hearth. they can also be cut easily with an old wood saw to any desired size. just make sure they are well dried out before using.

cheers,

julian

Ken,

By an amazing coincidence I finally got round to trying the pieces I salvaged out of our old gas fire last night to harden a home-made half centre.

I hadn't seen your post and so wasn't sure it'd work but it did - perfectly.

Jon

"GasMiser" radiants? Been using them for years.

Regards Ian.

Beware, some old gas fires might have Asbestos in them!

Edited By V8Eng on 21/07/2014 10:38:12

I've been using the bricks from storage heaters for many years. The ones I use are 'brick' shaped, but larger, and I built a dwarf wall with the fancier sheaped ones! A work colleague threw out two of these heaters, and I pounced!

Ted, you dont want bricks that retain heat, you want bricks that deflect and dont absorb the heat.

vermiculite blocks are available on line and ebay for very reasonable prices.

after silver soldering i can pick up all my bricks with my fingers/ hands after a minute or so.

cheers,

julian

Sharp edges too.

Julian

Point taken, but my bricks were free, and one man's reasonable price is another's big expense!

Cheers

Ted

I have two big (16" square, 1" thick) blocks of skamolex. I haven't use them to make a hearth yet as I want to have some sort of protective layer to stop flux sticking and eroding it away.

What would the panel suggest as a non-messy thin layer that will resist the heat and not let flux drip through?

I wondered about a piece of fire blanket, but I imagine it would melt at the temperatures for silver soldering/brazing.

Neil

Zircon paint.

Or... A thin hard firebrick (not excessive thermal mass, fantastic flux resistance). Or ceramic board coated with zircon paint. Or one of the asbestos substitute boards (like the things bunsen burners used to be sat on at school). Slices of soft firebrick? Perhaps messy.

look at my album for a couple of photos of my boiler being soldered in an isokern chimney liner with a few offcuts of vermiculite sheet moved around as required.

Screwfix No Nosense Fire Cement would do.

Can someone tell me what they mean by 'zircon paint' and where and from whom it might be obtained?

What are its particular characteristics?

Jerry

.

Jerry,

A few seconds on google located this.

MichaelG.

Thanks for the link Michael, but that doesn't tell me anything. Its just a sales blurb, I would need to see an explanation of the chemistry before I used any unknown composition where high temperatures and naked flames are anticipated. The missing information of course is the composition of the binder.

The mention of Zircon above implied that the posters had actual experience. Zircon in that link is merely being used as a trade name (registered or otherwise). Zircon as we well know is a gemstone.

I am not doubting the claims made but surely the performance relies on the conversion of the Zircon into zirconia at high temperatures.

Jerry

I feel that the soft bricks are best thought of as expendable, I do a round of building sites scrounging what I can. You could get some nice ones at the retailer selling Log Burners. I'm a long way from town, or I'd be visiting a builders supply yard, they are sure to have a broken one or two.

Ian S C

I think it's fair to say I'm aware of zircon in its faceted form (and that zircon and cubic zirconia are *very* different).

The zircon paint I have came from Purimachos in Bristol (now Vitcas). Price has gone up a bit since I bought mine... **LINK** As far as the composition of the binder goes, I'd suggest asking them directly for the COSHH sheet. Another alternative (not sure of the flux resistance, but it's a good IR reflector) would be ITC-100.

It doesn't soak into ceramic fibre, it is just used to coat the top surface. Oh, and 5l lasts a very long time...

FWIW, I tend to regard all refractories as expendable. Hard firebricks get eaten by flux eventually too, it just takes a lot longer.