diff --git a/src/Drawable.js b/src/Drawable.js
index 975ca95..cc1d9ab 100644
--- a/src/Drawable.js
+++ b/src/Drawable.js
@@ -36,8 +36,10 @@ const getLocalPosition = (drawable, vec) => {
     // localPosition matches that transformation.
     localPosition[0] = 0.5 - (((v0 * m[0]) + (v1 * m[4]) + m[12]) / d);
     localPosition[1] = (((v0 * m[1]) + (v1 * m[5]) + m[13]) / d) + 0.5;
-    // Apply texture effect transform.
-    EffectTransform.transformPoint(drawable, localPosition, localPosition);
+    // Apply texture effect transform if the localPosition is within the drawable's space.
+    if ((localPosition[0] >= 0 && localPosition[0] < 1) && (localPosition[1] >= 0 && localPosition[1] < 1)) {
+        EffectTransform.transformPoint(drawable, localPosition, localPosition);
+    }
     return localPosition;
 };
 
diff --git a/src/PenSkin.js b/src/PenSkin.js
index fb0b0d9..1e500ba 100644
--- a/src/PenSkin.js
+++ b/src/PenSkin.js
@@ -154,6 +154,13 @@ class PenSkin extends Skin {
         return true;
     }
 
+    /**
+     * @returns {boolean} true if alpha is premultiplied, false otherwise
+     */
+    get hasPremultipliedAlpha () {
+        return true;
+    }
+
     /**
      * @return {Array<number>} the "native" size, in texels, of this skin. [width, height]
      */
@@ -181,8 +188,9 @@ class PenSkin extends Skin {
     clear () {
         const gl = this._renderer.gl;
         twgl.bindFramebufferInfo(gl, this._framebuffer);
-
-        gl.clearColor(1, 1, 1, 0);
+        
+        /* Reset framebuffer to transparent black */
+        gl.clearColor(0, 0, 0, 0);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
         const ctx = this._canvas.getContext('2d');
@@ -598,7 +606,7 @@ class PenSkin extends Skin {
             this._silhouetteBuffer = twgl.createFramebufferInfo(gl, [{format: gl.RGBA}], width, height);
         }
 
-        gl.clearColor(1, 1, 1, 0);
+        gl.clearColor(0, 0, 0, 0);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
         this._silhouetteDirty = true;
diff --git a/src/RenderWebGL.js b/src/RenderWebGL.js
index 05b35e2..f16b02d 100644
--- a/src/RenderWebGL.js
+++ b/src/RenderWebGL.js
@@ -1620,7 +1620,14 @@ class RenderWebGL extends EventEmitter {
             }
 
             twgl.setUniforms(currentShader, uniforms);
-
+            
+            /* adjust blend function for this skin */
+            if (drawable.skin.hasPremultipliedAlpha){
+                gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
+            } else {
+                gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
+            }
+            
             twgl.drawBufferInfo(gl, this._bufferInfo, gl.TRIANGLES);
         }
 
diff --git a/src/Skin.js b/src/Skin.js
index d5fcbb3..e0e7413 100644
--- a/src/Skin.js
+++ b/src/Skin.js
@@ -76,6 +76,13 @@ class Skin extends EventEmitter {
         return false;
     }
 
+    /**
+     * @returns {boolean} true if alpha is premultiplied, false otherwise
+     */
+    get hasPremultipliedAlpha () {
+        return false;
+    }
+
     /**
      * @return {int} the unique ID for this Skin.
      */
diff --git a/src/shaders/sprite.frag b/src/shaders/sprite.frag
index 055e9a2..a781baf 100644
--- a/src/shaders/sprite.frag
+++ b/src/shaders/sprite.frag
@@ -194,12 +194,6 @@ void main()
 		discard;
 	}
 	#endif // DRAW_MODE_colorMask
-
-	// WebGL defaults to premultiplied alpha
-	#ifndef DRAW_MODE_stamp
-	gl_FragColor.rgb *= gl_FragColor.a;
-	#endif // DRAW_MODE_stamp
-
 	#endif // DRAW_MODE_silhouette
 
 	#else // DRAW_MODE_lineSample