Former leo.

This is simply not true.

UV isn't for oil. It can be used for "watermarks" but not the old school style on currency. There are certain pigments that react to UV and glow flourescent.

Some of these are actually ALSO used on currency, as there are multiple types of anti-forgery techniques employed.

It makes zero sense to look for fingerprints on ballots that are handled by multiple people prior to being tabulated..

And if they were looking for prints, old school black powder still works best, is fast and effective.

PM claiming that there is no evidence the ballots had watermarks proves hes a shill or misinformed.

Even printers can create a nearly invisible dot pattern as a "watermark" as a signature as to what machine printed a document.

Edit:

A more logical reason uv is being used is to DISINFECT each document in case of any contamination. Viral, etc.

Other than that, it's to detect phosphor type chemicals. Ie: semen (unlikely), reactive pigments (likely)