White residue on Vanda orchid leaves?

[Callaslily]

Originally Posted by estación seca

I'm not sure what it is, but I think it might not be mineral residue from watering. I wonder whether some Vandas can produce waxy substances like a lot of Brassavolas. I just ignore it on my plants.

I'll try lemon, if that doesn't work, then I'll just ignore it. I'm worried about it because when I got them, the substance wasn't there. In 2 weeks, it became like this.