Collect dried, unfired clay scraps and filings, and place them on a glass work surface. Using a tissue blade or razor blade, chop the clay into a fine powder (Photo 1).
Add water, and use a plastic or stainless steel palette knife to blend the mixture into a thick paste (Photo 2). For a slip consistency, add a little more water, and blend again.
Store the paste or slip in a small, airtight container.