Well, while what you are saying is true, in the past 10 years I brought back a fair number of liquid-damaged boards, assuming the damage occurred fairly recently and no major damage was done to components (and the customer is very lucky). My question isn't about how to clear liquid damage, really.
I am trying to understand the intended application of these fibreglass pencils which I have never seen in person, I just saw one for the first time in my life on eBay.
So you're saying that the pencil is of no use to me because I mainly rework and repair mobile phones, laptops, and such?