Painting aircraft
That should go without saying.
All sharps should be avoided on all aircraft skins.
the slightest imperfection cause by any sharp, from a scraper or knife causes disimilar metal corrosion.
Hense the earlier post when someone mentioned getting there Aircraft painted by a non proffesional??
Absolutely no sharps what so ever.
THERE IS ALWAYS AN ALTERNATIVE.
I came across an Aircraft that had the entire design scored with a sharp object.
And the signs of corrosion when the Aircraft was down to bare metal were visable to the naked eye.
You will get chancers and cowboys in all walks of life, but if they could foresee the hidden dangers (speaks for itself).