PTFE Spray … a boon
Aluminium oxide is what causes it not to stick to glue. 
When the coating grows “in the wild”, it is very uneven, weak, and brittle. The glue sticks to the coating and not to the substrate (the AL). Anodizing a part requires that this initial coat of oxide be stripped off and that the part is perfectly oil-free. Then a new coat of oxide is “grown” onto the aluminum using a sulphuric acid bath and electricity so that it is uniform and much stronger. Then it can be dyed. The oxide coating looks like a honeycomb and can actually hold the liquid dye. Then they chemically seal the oxide matrix to give it a hard surface. Lastly, it is given a good bath.