Why are my potato crisps never crispy?

[CheshireDing]

I have a Spiraliser and have tried a few times now to make curly fries and potato crisps from it. I do as it says on the Internet but they never crisp up :(

I have tried them directly on to a tray, on a raised tray, leaving them on the side afterwards (thinking they would crisp up when out of the oven). What's going wrong, it's like eating hot wet potato (even though they have been in a hot oven for EVER) ? :(

Any ideas appreciated as nobody was too impressed with them at dinner yesterday.

Do you coat in oil? How thickly do you spread them on the tray?

Drizzle of oil all over (bit like when I do roasted veg really) and a bit of black pepper. Then I spread them out across the tray, not piled on top of each other. I don't understand why they always look some floppy, anaemic and raw :( sigh