blur layers

PRINT.md

@@ -30,6 +30,38 @@ Why both: vector stays razor-sharp at any size but is "clean"; the raster holds
 the worn-film texture but is resolution-limited. At 4 m you want the geometry
 crisp *and* the grain present — so use both as layers.
 
+## 2a. SVG layers (for post manipulation)
+
+Every SVG is organised into named **layers** (Inkscape `inkscape:groupmode="layer"`
+convention) — they open as toggleable layers in **Inkscape** and **Affinity
+Designer**, and as named groups in **Illustrator**:
+
+```
+Background          paper + gas-glow gradient
+Chamber optics      boundary + structural fan / wall lines
+Shock disk          the piston disk (body + bubbles/strokes + stains)
+Tracks · primary    primary interaction tracks
+Tracks · cosmic & sweepers
+Tracks · V-decays
+Tracks · δ-rays (curls)   the little spirals, isolated for separate treatment
+Plate damage        scratches, hairs, dust, water rings
+Fiducials           registration crosses
+Vignette            edge darkening
+Archival header     lab / seed / plate / exposure text
+```
+
+So you can, e.g., recolour just the δ-rays, delete the header, mask the disk, or
+push the plate-damage layer to a different blend — without touching the rest.
+(Empty layers for a given seed are omitted.)
+
+**PDF layers too.** The PDF carries the same set as **Optional Content Groups
+(OCG)** — toggleable layers in Acrobat, Illustrator and Preview.
+
+**SVG effects.** SVG supports filters; the **Shock disk** layer carries an
+optional `feGaussianBlur` ("Disk edge softness" slider / `diskSoften`) to soften
+just that layer's edges. It's matched in the raster preview/PNG. (The PDF keeps
+the disk crisp — apply blur in post there, or use the PNG/SVG for the soft look.)
+
 ## 3. Recommended assembly (in your compositor)
 
 Think of each plate as a small stack you drop into your larger artwork: