DIRECT EMULSIONS & CDF DIRECT-FILMS | Solid Step 7
When you develop the stencil, areas that didn’t get enough exposure to survive development will dissolve with water and rinse down the drain. You want a minimum of a Solid Step 7 that survives and holds in the mesh. More exposure will make your stencil more durable and less will make the stencil less durable.
The guide numbers are clear on the film so they get 100% exposure. You will know you have a Solid Step, because you won't see a difference between the guide number, (7), and the patch of stencil around it. If you have a 'crusty' step, you know that unexposed stencil on the inside of the screen has broken down and washed away with water. Not Solid!
The great thing about a Stouffer 21 Step Transmission Gray Scale is that it only costs from US$6.00 to US$12.00 and should last a lifetime. The 21 Step is a real photographic positive with 21 steps of opacity that simulates 21 different exposures - with one exposure. Much faster than than a manual step test, where you have to move a piece of cardboard or Rubylith to block UV energy.