What sort of needle should I use when sewing plastic on my Bernina?

Answer 1

Use a sharp rather than a universal or ball point needle. Sharps are very pointy, where a ball point has a rounded tip for use with knits. The rounded tip goes between the threads and won't snag them. Universal tips are somewhere between sharps and ball points.

The thinness of the needle depends on what kind of plastic you're sewing. If it's fairly thin, flexible plastic, use a thinner needle because plastic won't "heal" the needle holes like fabric does. The thicker the plastic, the larger the needle you will need because you need a fairly strong needle to go through such tough material. Unless it's a really thick plastic, I'd try a size 12 or 14 needle (that's US sizes - in European sizes it would be 80 or 90).

Also, try putting a piece of wax paper on your machine bed, under the plastic that you're sewing. This will keep it from sticking to your machine. If you have a walking foot, use it to help move the plastic along, rather than relying solely on the feed dogs.

Answer 2

I think you should best use a thin needle.
The bigger the needle, the bigger the hole, and the plastic might tear up at the holes.