Kitchen Garden Forum

I read an article on another website about making demijars into cloches by sitting the bottle in iced water and filling to the level you want the glass to break at with boiling water, the first one I tried worked perfectly, clean break about an inch up from the bottom, but then the next one cracked right up the side and none of the others (I had 6 all together) would break at all. Does anyone know a foolproof method of doing this, without any special equipment?

You can get a glass cutter from craft supplies. I assume it works!

I seem to remember there's also a trick with string and something - maybe just Google it as a question.

A friend of mine used to cut glass by tightly wrapping wire round the glass at the point he wanted it to break. He then heated the wire (can't recall how, candle I think) and then tapped the glass to break it. Long time ago but I think it worked.

I made them some years ago. Think I used a combination of these methods, ie first score round with a glass cutter where you want it to break, then put demijohn in cold water to above the score mark and pour in boiling water. Worked every time I seem to remember.
Good luck,
Chris

Borrowed this from another forum - hope it helps.

All you need is one of those hand held glass cutters with the little wheel on it and a work bench or a table top vice so you can clamp the glass cutter with the wheel rotating horizontally about an inch off the work surface.

With the glass cutter firmly clamped in place you score the groove around the bottle by resting it on the work surface and then rotating it while pressing it against the cutter wheel. Try and get a single score mark which is joined up all the way around

Then you need to fashion youself something like a quarter of an inch thick metal rod with a slight bend about a couple of centimetres from one end. The shape and length of this is quite important since you are going to use to stick down the inside of the demijohn.

You use this to tap lightly at the score line from the inside of the bottle. If you tap fairly lightly you will get a slight crack forming at that point. Then you move another half a centimetre along the score line and tap again and the crack will follow the line you have scored on the outside of the bottle. If you are gentle with the tapping the crack will run true and follow the score line.

As you work your way round the sound made by the tapping starts to get quite dull, which is a warning that both parts will soon part company. When the crack is completely joined up, your new bell jar will part company with your new flowerpot tray!

Tip: Giving the demijohn bit of a wash in warm water helps and working in the warm also makes the glass a bit easier to work with too.

For safety sake you may want to think about using rubber gloves and wearing goggles or glasses when you are cutting the glass. Also you can give the bottom edges of the demijonn a good twist on sandy soil to make them less sharp.

If you don't have any demijohns its worth keeping your eyes open at the local glass recycling point.

As an alternative to tapping from the inside, tie a single line of string around the cut, soak in lighter fuel, put the jar on it's side and ignite the fuel. As soon as the flames die out dunk the jar bottom first in some cold water, and the base usually cracks right off. I say usually because there are sometimes flaws in the glass. A slightly riskier method certainly, but immensly satisfying when it works. Needless to say, Gloves, Mask, Goggles!!

That's a very helpful reference Belinda. We have several gallon demijohns in our loft which I'm wondering to convert to cloches if their winemaking days are over. So far I've been using some large plastic drinking water fountain containers which make ideal cloches and are much easier to deal with by means of a hacksaw, but these are like gold dust to obtain. I can't believe the prices being charged for plastic bell-type cloches in garden centres.

I'm not sure about the dimensions, i.e. height & width but this company http://www.art-of-brewing.co.uk sell plastic demijohns @ £2.49 each.

FREE DELIVERY for UK mainland orders over £49. Only £4.95 for UK mainland orders of £19 to £49. For goods valued at less than £19 we charge a higher rate of £6.49 for handling and shipping, this reflects the cost of processing to profit ratio. For the aforementioned rates the delivery service is 48 Hour. Express 24 Hour delivery is available at an extra charge.

So I guess it depends on how many you want and if they're of a usable size.

What a great idea I must try it. I use a demijohn as a slug pot. I leave some salty water in it and pop any slugs I find in it.