diff --git a/deploy/site/ambient.js b/deploy/site/ambient.js
index eb49625..e4f6613 100644
--- a/deploy/site/ambient.js
+++ b/deploy/site/ambient.js
@@ -78,7 +78,15 @@
     for (let i = 0; i < message.length; i++) seed = Math.imul(seed ^ message.charCodeAt(i), 16777619);
     return seed >>> 0;
   }
-  if (typeof module !== 'undefined') module.exports = { createCurrent, position, receive, absorb, resizeCurrent };
+  function grainFrom(seed) {
+    const random = randomFrom(seed);
+    return Array.from({ length: 4200 }, () => {
+      const x = random() * 384, y = random() * 384;
+      const direction = Math.sin(x / 47) * .4 + Math.cos(y / 61) * .3;
+      return { x, y, length: .6 + random() ** 3 * 2.8, direction, alpha: .12 + random() ** 2 * .25 };
+    });
+  }
+  if (typeof module !== 'undefined') module.exports = { createCurrent, position, receive, absorb, resizeCurrent, grainFrom };
   if (typeof document === 'undefined') return;
   const canvas = document.querySelector('canvas[data-current]');
   if (!canvas) return;
@@ -88,6 +96,26 @@
   const reduced = matchMedia('(prefers-reduced-motion: reduce)');
   let width = 0, height = 0, frame = 0, last = 0, entropy = 0;
   let socket, retry;
+  let grain, grainSeed;
+  function texture() {
+    if (grain && grainSeed === current.seed) return grain;
+    const tile = document.createElement('canvas');
+    tile.width = tile.height = 768;
+    const surface = tile.getContext('2d');
+    surface.scale(2, 2);
+    for (const fleck of grainFrom(current.seed)) {
+      surface.strokeStyle = `rgba(145,168,161,${fleck.alpha})`;
+      surface.lineWidth = .65;
+      surface.beginPath();
+      surface.moveTo(fleck.x, fleck.y);
+      surface.lineTo(fleck.x + fleck.length, fleck.y + fleck.direction * fleck.length);
+      surface.stroke();
+    }
+    grain = context.createPattern(tile, 'repeat');
+    grain.setTransform(new DOMMatrix().scale(.5));
+    grainSeed = current.seed;
+    return grain;
+  }
   function connect() {
     clearTimeout(retry);
     if (document.hidden || socket) return;
@@ -101,6 +129,7 @@
   function paint(now) {
     const phase = reduced.matches ? current.to : position(current, now);
     const t = reduced.matches ? 1 : progress(current, now);
+    const surface = texture();
     context.clearRect(0, 0, width, height);
     for (const shard of current.shards) {
       const points = shard.points.map(([x, y]) => [x * width, y * height]);
@@ -111,6 +140,10 @@
       context.moveTo(...a); context.lineTo(...b); context.lineTo(...c); context.closePath();
       context.fillStyle = `rgba(${pigment},${.012 + light * .025})`;
       context.fill();
+      context.fillStyle = surface;
+      context.globalAlpha = .65 + light * .35;
+      context.fill();
+      context.globalAlpha = 1;
       context.save(); context.clip();
       const offset = (shard.tint - .5) * 14;
       for (let channel = 0; channel < 4; channel++) {
diff --git a/deploy/site/index.html b/deploy/site/index.html
index 6fbb558..6671193 100644
--- a/deploy/site/index.html
+++ b/deploy/site/index.html
@@ -81,7 +81,7 @@ footer .icon{width:11px;height:11px;vertical-align:-1px;margin-right:.6ch}
   <a href="https://tangled.org/zat.dev/stream">source</a>
 </footer>
 </div>
-<script src="/ambient.js?v=shards-2"></script>
+<script src="/ambient.js?v=grain-1"></script>
 <script>
 const $ = (id) => document.getElementById(id);
 const fittedLines = document.querySelectorAll('.ep .p, .ep .d, .tag');
diff --git a/tests/glass-current.test.cjs b/tests/glass-current.test.cjs
index bc617b2..6ddd2b3 100644
--- a/tests/glass-current.test.cjs
+++ b/tests/glass-current.test.cjs
@@ -1,6 +1,16 @@
 const { test } = require('node:test');
 const assert = require('node:assert/strict');
-const { createCurrent, receive, position, absorb, resizeCurrent } = require('../deploy/site/ambient.js');
+const { createCurrent, receive, position, absorb, resizeCurrent, grainFrom } = require('../deploy/site/ambient.js');
+
+test('surface grain stays fixed while live light and viewport change', () => {
+  const field = createCurrent();
+  receive(field, 1000n, 0, 123n);
+  const surface = grainFrom(field.seed);
+  receive(field, 2000n, 5000, 456n);
+  resizeCurrent(field, 1920, 1080);
+  assert.deepEqual(grainFrom(field.seed), surface);
+  assert.notDeepEqual(grainFrom(2000n), surface);
+});
 
 test('wide screens gain facets instead of stretching the mobile glass', () => {
   const field = createCurrent();