This time I used a 50/50 mix of white vinegar and water. I wrapped the nails and some pieces of iron up in the prewashed and wet cotton shirting fabric. I poured the vinegar/water mix over this in a shallow basin. Then I set it in the sun for several days turning it over every now and then. Once the process was complete I washed the fabric in salted water. I was delighted with the result. I can see possible boulders and trees in the rust imprints.