[John]

I looked up some info on the topic, and found this website:

https://www.thyssenkrupp-materials.co.uk/does-aluminium-rust

Essentially, aluminum doesn’t rust, but it does corrode due to various factors. I think the edge that’s exposed is small enough that if corrosion does occur, it won’t affect much. The article goes into detail on what causes aluminum to corrode.

thyssenkrupp-materials.co.uk

Does aluminium rust. Click to find out more. thyssenkrupp Materials (UK)

Aluminium is an extremely popular metal and is used in a vast number of applications but, does it rust?

[John]

Hi Ann,

I’m unfamiliar with the Schminke medium of which you speak, but I can offer some advice on underpaintings:

It is indeed good practice to let the underpainting become touch-dry before adding the color layer on top. Otherwise you risk lifting the underpainting and/or getting the underpainting’s color mixed in with the colors you’re laying on top. I think it is ok to use some linseed oil to get a thinner layer, but keep it to an absolute minimum if possible. Then make sure you let the underpainting dry (do the touch-dry test where you place the tip of your thumb – not your thumbnail – onto the painting, then press down. If any paint lifts off or smudges, it’s not yet touch-dry).