 Re: how do i remove dried blockout from screen..
Most blockouts are water soluble; more so than most emulsions. The trick to selective removal is to avoid excessive abrasion (rubbing) to get it off.
Use a cotton ball or piece of paper towel to rewet the blockout before removal. You can usually blot out the dissolving blockout with more blotter material, or a Q-tip, without damaging the stencil.
In extreme circumstances, your screen emulsion can also be re-rinsed in the washout booth, removing all blockout and doing the drying and blocking step all over. Just be careful with water spray pressure.
An excellent tool for close-up pinholing is known as a "Blockout Pen"; kind of like a pressurized syringe for heavy volume touchup.
Good luck! | 
