MMC question

    Hi all.
My name is michael and I am new(ish) tp this list.

I would like to know if standard metallised polyester greencaps will
work at all in a coil. I was recently given a few hundred (like 500) of
these each rated at 100Vdc and 0.49uF.

I understand that these are probably undesirable, however it's all i've
got at the moment (other to a 2nF rolled cap that's too small for my

I would also like to know if  "Plastic film Boxed casing MKT 250V" caps
will work. I have made a few bricks (5" X .5") of 360 each, but am
worried about blowing them when they have other uses. They are each
rated 250V and 0.022uF.

My other question is this.
I am running a 4" coil with 16 (30 degrees incline) turns of 3.5mm Iron?
fencing wire for the primary.
My spark gap consists of up to 10 X 0.5mm gaps.
I'm using 3 15Kv 30mA NSTs and am only getting 12" discharges.
My cap is a 20nF (about) rolled PE type.
I've raised the secondary to reduce coupling but to no avail.
Does anyone have any suggestions??

Thank you very much for your time.