Ok I've recieved an email, thank you Connie, and the question is: "OK I tried your method but there's still rust on the surface"! Now what?
Good question! Here is a partial copy of my email reply:
Is it heavily crusted on the fabric? I left mine overnight in order to remove rust, it doesn't remove all of it, from the fabric, I should have clarified that in my orignal post. For the heavily crusted fabric I did the direct method and NOTE I ended up with holes where the baking soda really went to town, something else I forgot to mention that might happen - my bad!
Also water type may play a role in this, doesn't it always. What is your water's pH? Sometimes a little soda ash helps to get the pH closer to 7.5, which is what you will need to budge the rust off the surface.
AGAIN it may not remove ALL of the rust off the surface. My goal for removing rust from the fabrics surface wasn't so much to remove the color as it was to help those who had rather stiff fabrics, due to rust build up, so that they could stitch the fabric with ease.
I'll post pictures tomorrow of the rust removal direct method - I have lots of holes to share but my fabric is supple again, which makes stitching a joy.