Recently we painted with oil. Cooking oil. In fact, I poured our medium from the bottle in my pantry.
We were talking about a Bible story with oil in it. So I wanted kids to have some experience with oil. So often kids just see it in that bottle in the pantry, if at all.
So, oil in small bowls with cotton swabs to use as "brushes." I provided colored construction paper because the oil shows up well on the colors. Then it seeps into the paper and the design stays visible after it dries.
A few kids experimented with letters and designs.
Then one friend came to the table and began to work.
He painted a few swirls, put the paper aside, and picked up a new piece of paper.
He did this several times, stacking all his oily papers together in an odd sandwich. He also discovered that if you use a cotton swab with oil for a while, it begins to droop and even pull apart.
Then he experimented with using more than one swab at a time. Which put even more stress on the swabs.
But that's fine. I had a bag of cotton swabs. And discovery is often messy and surprising and a little out of the box.
I wouldn't want it any other way.