This is original png file.
https://ibb.co/wNcfdrc

...and this is what I save from FXPaint after.
https://ibb.co/qDrzj3K

I use this images in Lightwave, one for original texture and second bw for alpha transparency.
I was try only smoke effect (90 images converted in fx paint) and its looks great rendered in LW, but its was very time consuming to save 90 images one by one.
Hope this help and thank you