Two facts share a glove box: ZnSe scratches if you look at it, and ZnSe is a selenium compound. The first ruins the coating. The second ruins an EHS audit.
Soft
Knoop hardness around 105–120. Fingerprints etch stories into an uncoated face. A steel tweezer is a generating tool. Edge chips on cores are specified because they happen. We inspect; we do not pretend the crystal is fused silica. Always gloves. Never dry paper towels. Never a shirt tail.
Hazardous
The solid window is not H2Se. Dust from grinding, slurry, and thermal decomposition products are still selenium-bearing. Do not dry-grind. Use wet process and extraction. Read the SDS before the first blank hits a spindle. Current file: KM Innovation Zinc Selenide SDS (PDF).
Shipping and end of life
Hazardous-material rules can apply to the shipment depending on form, quantity and carrier. Tell us the destination country on the RFQ so the paperwork matches the crate. At end of life we will take windows and broken blanks back for proper disposal — email the Florida desk. That offer is older than this website. Use it. Do not teach a landfill selenium chemistry.
None of this makes ZnSe “too dangerous to use.” It makes it a material with an SOP. Laser shops that already handle it do not find this exciting. First-time buyers who treat it like acrylic do.