diff --git a/render-worker/scripts/asset_library.py b/render-worker/scripts/asset_library.py
index 895c8a9..e611c6f 100644
--- a/render-worker/scripts/asset_library.py
+++ b/render-worker/scripts/asset_library.py
@@ -13,13 +13,16 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-def apply_asset_library_materials(blend_path: str, material_map: dict) -> None:
-    """Link materials from an asset library .blend and apply them to mesh slots.
+def apply_asset_library_materials(blend_path: str, material_map: dict, link: bool = True) -> None:
+    """Load materials from an asset library .blend and apply them to mesh slots.
 
     Args:
         blend_path: Absolute path to the .blend library file.
         material_map: Mapping of current slot material name -> library material name.
                       E.g. {"Steel--Stahl": "SCHAEFFLER_010101_Steel-Bare"}
+        link: If True (default), link materials (external reference, good for rendering).
+              If False, append materials (local copy — required for GLB/GLTF export so
+              that the exporter can traverse Principled BSDF node trees for PBR values).
     """
     import bpy  # type: ignore[import]
 
@@ -28,12 +31,12 @@ def apply_asset_library_materials(blend_path: str, material_map: dict) -> None:
 
     target_names = set(material_map.values())
 
-    # Link materials from the library
-    with bpy.data.libraries.load(blend_path, link=True, assets_only=True) as (src, dst):
+    # Link or append materials from the library
+    with bpy.data.libraries.load(blend_path, link=link, assets_only=True) as (src, dst):
         dst.materials = [name for name in src.materials if name in target_names]
 
-    linked = {m.name for m in dst.materials if m is not None}
-    logger.info("Linked %d materials from %s", len(linked), blend_path)
+    loaded = {m.name for m in dst.materials if m is not None}
+    logger.info("%s %d materials from %s", "Linked" if link else "Appended", len(loaded), blend_path)
 
     # Apply to all mesh object material slots
     for obj in bpy.data.objects:
diff --git a/render-worker/scripts/export_gltf.py b/render-worker/scripts/export_gltf.py
index 4a0195e..3be4207 100644
--- a/render-worker/scripts/export_gltf.py
+++ b/render-worker/scripts/export_gltf.py
@@ -113,20 +113,26 @@ def main() -> None:
         mark_sharp_edges_by_proximity(sharp_edge_midpoints)
         print(f"Marked sharp edges from {len(sharp_edge_midpoints)} hint points")
 
-    # Apply asset library materials if provided
+    # Apply asset library materials if provided.
+    # link=False (append) is required for GLB export: the GLTF exporter can only
+    # traverse local (appended) Principled BSDF node trees to extract PBR values.
+    # Linked materials are external references whose node data is not accessible.
     if args.asset_library_blend and material_map:
         import os
         sys.path.insert(0, os.path.dirname(__file__))
         from asset_library import apply_asset_library_materials
-        apply_asset_library_materials(args.asset_library_blend, material_map)
+        apply_asset_library_materials(args.asset_library_blend, material_map, link=False)
 
-    # Export GLB
+    # Export GLB with full PBR material data
     try:
         bpy.ops.export_scene.gltf(
             filepath=args.output_path,
             export_format="GLB",
             export_apply=True,
             use_selection=False,
+            export_materials="EXPORT",       # export all materials (Principled BSDF → glTF PBR)
+            export_image_format="AUTO",      # embed textures (base color, normal, roughness maps)
+            export_colors=False,             # skip vertex colors (we use library materials)
         )
     except Exception as exc:
         print(f"GLB export failed: {exc}", file=sys.stderr)