diff --git a/source/engine/model/material.js b/source/engine/model/material.js
index a77a19c..1fa4404 100644
--- a/source/engine/model/material.js
+++ b/source/engine/model/material.js
@@ -70,12 +70,19 @@ export const MaterialType =
     Physical : 2
 };
 
+export const MaterialSource =
+{
+    Model : 1,
+    DefaultFace : 2,
+    DefaultLine : 3
+};
+
 export class MaterialBase
 {
     constructor (type)
     {
         this.type = type;
-        this.isDefault = false;
+        this.source = MaterialSource.Model;
 
         this.name = '';
         this.color = new RGBColor (0, 0, 0);
@@ -88,7 +95,7 @@ export class MaterialBase
         if (this.type !== rhs.type) {
             return false;
         }
-        if (this.isDefault !== rhs.isDefault) {
+        if (this.source !== rhs.source) {
             return false;
         }
         if (this.name !== rhs.name) {
diff --git a/source/engine/model/modelfinalization.js b/source/engine/model/modelfinalization.js
index e9475eb..97cac35 100644
--- a/source/engine/model/modelfinalization.js
+++ b/source/engine/model/modelfinalization.js
@@ -1,15 +1,9 @@
 import { CopyObjectAttributes } from '../core/core.js';
 import { AddCoord3D, Coord3D, CoordIsEqual3D } from '../geometry/coord3d.js';
 import { RGBColor } from './color.js';
-import { PhongMaterial } from './material.js';
+import { MaterialSource, PhongMaterial } from './material.js';
 import { CalculateTriangleNormal, IsEmptyMesh } from './meshutils.js';
 
-const MaterialSource =
-{
-    Line : 1,
-    Face : 2
-};
-
 class ModelFinalizer
 {
     constructor (params)
@@ -148,7 +142,7 @@ class ModelFinalizer
         for (let i = 0; i < mesh.LineCount (); i++) {
             let line = mesh.GetLine (i);
             if (line.mat === null) {
-                line.mat = this.GetDefaultMaterialIndex (model, MaterialSource.Line);
+                line.mat = this.GetDefaultMaterialIndex (model, MaterialSource.DefaultLine);
             }
         }
 
@@ -156,7 +150,7 @@ class ModelFinalizer
             let triangle = mesh.GetTriangle (i);
             this.FinalizeTriangle (mesh, triangle, meshStatus);
             if (triangle.mat === null) {
-                triangle.mat = this.GetDefaultMaterialIndex (model, MaterialSource.Face);
+                triangle.mat = this.GetDefaultMaterialIndex (model, MaterialSource.DefaultFace);
             }
         }
 
@@ -211,22 +205,22 @@ class ModelFinalizer
 
     GetDefaultMaterialIndex (model, source)
     {
-        function GetIndex (model, index, color)
+        function GetIndex (model, index, source, color)
         {
             if (index !== null) {
                 return index;
             }
             let defaultMaterial = new PhongMaterial ();
             defaultMaterial.color = color;
-            defaultMaterial.isDefault = true;
+            defaultMaterial.source = source;
             return model.AddMaterial (defaultMaterial);
         }
 
-        if (source === MaterialSource.Line) {
-            this.defaultLineMaterialIndex = GetIndex (model, this.defaultLineMaterialIndex, this.params.defaultLineMaterialColor);
+        if (source === MaterialSource.DefaultLine) {
+            this.defaultLineMaterialIndex = GetIndex (model, this.defaultLineMaterialIndex, MaterialSource.DefaultLine, this.params.defaultLineMaterialColor);
             return this.defaultLineMaterialIndex;
-        } else if (source === MaterialSource.Face) {
-            this.defaultMaterialIndex = GetIndex (model, this.defaultMaterialIndex, this.params.defaultMaterialColor);
+        } else if (source === MaterialSource.DefaultFace) {
+            this.defaultMaterialIndex = GetIndex (model, this.defaultMaterialIndex, MaterialSource.DefaultFace, this.params.defaultMaterialColor);
             return this.defaultMaterialIndex;
         } else {
             return null;
diff --git a/source/engine/model/modelutils.js b/source/engine/model/modelutils.js
index 8bb131d..70724b1 100644
--- a/source/engine/model/modelutils.js
+++ b/source/engine/model/modelutils.js
@@ -1,5 +1,6 @@
 import { BoundingBoxCalculator3D } from '../geometry/box3d.js';
 import { Octree } from '../geometry/octree.js';
+import { MaterialSource } from './material.js';
 import { IsEmptyMesh } from './meshutils.js';
 import { Model } from './model.js';
 import { Topology } from './topology.js';
@@ -99,7 +100,7 @@ export function HasDefaultMaterial (model)
 {
     for (let i = 0; i < model.MaterialCount (); i++) {
         let material = model.GetMaterial (i);
-        if (material.isDefault && !material.vertexColors) {
+        if (material.source !== MaterialSource.Model && !material.vertexColors) {
             return true;
         }
     }
@@ -110,7 +111,7 @@ export function ReplaceDefaultMaterialsColor (model, color)
 {
     for (let i = 0; i < model.MaterialCount (); i++) {
         let material = model.GetMaterial (i);
-        if (material.isDefault) {
+        if (material.source === MaterialSource.DefaultFace) {
             material.color = color;
         }
     }
diff --git a/source/engine/threejs/threeconverter.js b/source/engine/threejs/threeconverter.js
index 1625eb2..7e93343 100644
--- a/source/engine/threejs/threeconverter.js
+++ b/source/engine/threejs/threeconverter.js
@@ -1,7 +1,7 @@
 import { RunTasksBatch } from '../core/taskrunner.js';
 import { IsEqual } from '../geometry/geometry.js';
 import { CreateObjectUrl, CreateObjectUrlWithMimeType } from '../io/bufferutils.js';
-import { MaterialType } from '../model/material.js';
+import { MaterialSource, MaterialType } from '../model/material.js';
 import { MeshInstance, MeshInstanceId } from '../model/meshinstance.js';
 import { IsEmptyMesh } from '../model/meshutils.js';
 import { ConvertColorToThreeColor, GetShadingType, ShadingType } from './threeutils.js';
@@ -204,7 +204,8 @@ export class ThreeMaterialHandler
 			threeMaterial.emissiveMap = threeTexture;
 		});
 
-		if (material.isDefault) {
+		if (material.source !== MaterialSource.Model) {
+			threeMaterial.userData.source = material.source;
 			this.conversionOutput.defaultMaterials.push (threeMaterial);
 		}
 
@@ -225,7 +226,8 @@ export class ThreeMaterialHandler
 		}
 
 		let threeMaterial = new THREE.LineBasicMaterial (materialParams);
-		if (material.isDefault) {
+		if (material.source !== MaterialSource.Model) {
+			threeMaterial.userData.source = material.source;
 			this.conversionOutput.defaultMaterials.push (threeMaterial);
 		}
 
diff --git a/source/engine/threejs/threemodelloader.js b/source/engine/threejs/threemodelloader.js
index 7be28f6..bb695cf 100644
--- a/source/engine/threejs/threemodelloader.js
+++ b/source/engine/threejs/threemodelloader.js
@@ -1,6 +1,7 @@
 import { Direction } from '../geometry/geometry.js';
 import { Importer } from '../import/importer.js';
 import { RevokeObjectUrl } from '../io/bufferutils.js';
+import { MaterialSource } from '../model/material.js';
 import { ConvertModelToThreeObject, ModelToThreeConversionOutput, ModelToThreeConversionParams } from './threeconverter.js';
 import { ConvertColorToThreeColor, HasHighpDriverIssue } from './threeutils.js';
 
@@ -95,7 +96,7 @@ export class ThreeModelLoader
     {
         if (this.defaultMaterials !== null) {
             for (let defaultMaterial of this.defaultMaterials) {
-                if (!defaultMaterial.vertexColors) {
+                if (!defaultMaterial.vertexColors && defaultMaterial.userData.source === MaterialSource.DefaultFace) {
                     defaultMaterial.color = ConvertColorToThreeColor (defaultColor);
                 }
             }
diff --git a/source/website/sidebardetailspanel.js b/source/website/sidebardetailspanel.js
index cc998c8..4981c01 100644
--- a/source/website/sidebardetailspanel.js
+++ b/source/website/sidebardetailspanel.js
@@ -7,7 +7,7 @@ import { AddDiv, AddDomElement, ClearDomElement } from '../engine/viewer/domutil
 import { SidebarPanel } from './sidebarpanel.js';
 import { CreateInlineColorCircle } from './utils.js';
 import { GetFileName, IsUrl } from '../engine/io/fileutils.js';
-import { MaterialType } from '../engine/model/material.js';
+import { MaterialSource, MaterialType } from '../engine/model/material.js';
 import { RGBColorToHexString } from '../engine/model/color.js';
 import { Unit } from '../engine/model/unit.js';
 
@@ -104,7 +104,8 @@ export class SidebarDetailsPanel extends SidebarPanel
         } else if (material.type === MaterialType.Physical) {
             typeString = 'Physical';
         }
-        this.AddProperty (table, new Property (PropertyType.Text, 'Source', material.isDefault ? 'Default' : 'Model'));
+        let materialSource = (material.source !== MaterialSource.Model) ? 'Default' : 'Model';
+        this.AddProperty (table, new Property (PropertyType.Text, 'Source', materialSource));
         this.AddProperty (table, new Property (PropertyType.Text, 'Type', typeString));
         if (material.vertexColors) {
             this.AddProperty (table, new Property (PropertyType.Text, 'Color', 'Vertex colors'));