It's easy when you design the piece you are making to complement the patterning you are using. I do cheat a little because I design my own line of texture mats geared towards ceramic applications! You can find them on my Etsy site - https://www.etsy.com/shop/BHClaysmith?section_id=13035613&ref=shopsection_leftnav_7
Sodium Hexametaphosphate is the original "Calgon" formula plus perfume which was made in the US awhile back. It was reformulated due to the adverse effect the chemical had on the the microscopic flora in streams and rivers but can still be purchased from certain chemical supply houses. I believe it is used by people involved with pool cleaning.
Here are the recipes for two really nice ocher terra sigillata mixes. Since Albany Slip is no longer available, you can make the Weiser Ocher one instead which is just as nice!
ALBANY SIG
50 grams Albany slip
50 grams KYOM4
400 grams water
10 grams Sodium Hexametaphosphate
OCHRE SIG by Weiser
1663 grams Cedar Heights Gold Art
66 grams Yellow Ochre
Add to a mixture of:
8 grams soda ash
16 grams Sodium Hexametaphosphate
1 gallon water
Black Walnut and Laguna 40 stoneware clays combine to form this 16" high hand built bottle. It is glazed with Falls Creek Shino and electric fired to cone 6.