People say white means needs wax, but this usually isn't true, especially on the edges. There's no way that is "dryness" white in that pic. If you can scratch it off with your nail, it's not lacking wax. If it's faint, dry, and hairy looking, that's another story. Yours just looks like a freshly waxed board that someone rode the edges on.
Since it's probably not dry, it's either base burn, or excess wax. Try scraping better, and let the board cool before scraping. If you scrape when it's too warm, then as the base dries and the base material contracts, it pushes more wax out. (Edit: Odd, poster above suggests the opposite experience. Try both I guess.)
If it's base burn, you need a grind. I doubt it's base burn though, because it's on the edges and is more consistent with the areas favored while riding the board as opposed to being consistent with where the iron was left on. Base burn is from bad iron usage and tends to be patches. Base burn does not happen from a kid learning to link turns and favoring edges a lot. It isn't base burn. Ptex is WAY stronger than that.
Read this for causes of white areas on a base. Contrary to often repeated advice, lacking wax is the least likely of causes:
SkiWax.ca White Patch On Ski Base
I have one board with a sintered base that hasn't been waxed in about 10 years. It's not nearly that white. If you scratch it, you can't scratch the dry off. Obviously.
If you scratch your nail across that one, and it comes off, it's the opposite of a dry spot. It's wax! So you're re-waxing too soon. It won't hurt anything but it's a waste of time/wax.
Scratch your nail into it and say what happens. If your nail doesn't leave a dark spot among the white/gray, taking some residue off, and it is in fact bone dry, I will be very shocked.
I see people get white edges after a day out, look at their board, leave a big trail in it with their fingernail, and say "I guess that means it's time to wax!" Wtf, how does that make sense?
get the kids to help out, mine like to help with waxing, athough they're scraping skills aren't great. they're good at putting wax on and not bad at brushing.
Probably a bad idea. Wax fumes are highly toxic. I wouldn't go out of my way to expose children to it. There are studies where they have found high levels of all kinds of bad shit in the blood of shop techs (from the wax). Source: http://www.scientificamerican.com/ar...buildup-blood/