I stitched two samples on calico using a thin and a thick cotton thread.

These were then coated with gesso.

I layered and rubbed back the first one with acrylic paints hoping to get some sort of aged/distressed look...

...but it didn’t work so out came the Quinacridone Crimson followed by Treasure Gold!

The second one I painted with Koh-i-noor dyes. Red first followed by navy then rubbed over with bleach. The first picture shows the effect almost as soon as I put the bleach on and the second picture is after it had dried out.

What I really got excited about though was this technique. It didn’t really work as a sample but I still liked the effect.
I laid a piece of household tin foil over the calico and thick thread sample and rubbed hard to get an impression in the foil. I painted this over with Gel Medium to hold the impression in place and sprinkled coarse sea salt on. You can just see the outline of the stitches in this photo below.
Phthalo Turquoise paint was mixed with a small amount of Quinacridone Crimson and painted over the foil. This was followed by a coat of Quinacridone Gold.
These photos were taken while the paint was still slightly wet, but the effect is the same even when dry. If you double click on the first two photos above you will see a lovely twinkly starry effect caused by the reaction of the salt with the paint - I think!
Maybe the reason the stitches didn't show up better is because the foil is too thin to hold its shape. Next time I will either glue the foil on top of the stitches or perhaps use a craft foil.