In article ,
says...

I've lost 3 out of my 9 asparagus plants last Winter. I was looking for
something more robust than the usual 3L plastic water bottles.

I've got half a dozen surplus demijons, acquired from Council and car-boot
sales. To cut the bases off, first look at this video:-
http://lifehacker.com/5892147/cut-a-...tring-and-fire
My method is to use meths rather than nail polish remover.
I prefer to brush the meths, (about 5ml) rather than dip the string.
As per video, rotate rapidly for 45 seconds.
Plunge into bucket of cold water :-)
Clean edge with glasspaper (I used 120 grade aluminium oxide) Gloves
needed:-
http://s20.postimg.org/46gjawgx9/IMG_3986.jpg

My first attempt shattered after 2 mins. 2 mins is too long. The DJ is still
useable, but it took a lot of sanding to remove the jagged edges.
At only 45 seconds of heat, the next 5 DJs were good.
The cut-line doesn't follow the string, perhaps 10mm away??
The edge is a bit wavy, but for protecting delicate garden plants, just a
few seconds with
abrasives is all that's required.

what a good idea, thanks. Demijohns turn up in garage sales and
jumbles, must keep an eye out.

Janet