What type of paint pen do you use on the block basis cardstock

We would recommend metallic pens and markers for this stock.

Demo question for testing purpose only.

Hello Milan,

here is you answer for your content is working properly.

Can you put stickers on it or does the vellum coating make it peal off?

The vellum is not a coating it is the finish or the feel of the stock.  Yes, you should be able to add stickers to the card stock without them peeling off.

Is this product solid or white core?

This is a solid core card stock.  If you tear the card stock, the middle is black not white.