diff --git a/README.md b/README.md
index 3584eb6f734b08b0d53c1fe835ffb4df419961a1..68b4cc148062b39260b9400c7a30c04f30b05662 100644
--- a/README.md
+++ b/README.md
@@ -51,14 +51,17 @@ This package file includes launch files:
   * **yaw** (default=0.0) orientation of the traffic sign with respect to the parent frame.
   * **parent** (default=map) parent reference frame used to place the traffic sign in the simulated environment.
   * To change the semaphore light, publish on the /<name>_set_material_plugin/set_material topic.
-    * empty string will make the light to switch between green and red
-    * other features are under development.
+    * An empty string will make the light to switch between green and red
+    * Setting a [gazebo material](http://wiki.ros.org/simulator_gazebo/Tutorials/ListOfMaterials) (Gazebo/Red, Gazebo/Green, Gazebo/Orange, ...) will change the material accordingly.
 * spawn_localization_sign.launch. Under development.
 
 A test launch file is provided. To use it, execute the following command:
 
 ```
 roslaunch iri_sign_description spawn_test.launch
+
+rostopic pub -1 /semaphore1_set_material_plugin/set_material std_msgs/String "data: ''"
+rostopic pub -1 /semaphore2_set_material_plugin/set_material std_msgs/String "data: 'Gazebo/Orange'"
 ```
 
 ## Disclaimer
diff --git a/launch/spawn_semaphore.launch b/launch/spawn_semaphore.launch
index 6a81898012e99e3a126c3a66a3891dfd24d7bb09..5c7eebfce2c5c9bde68a41d3732ec240ecf424ae 100644
--- a/launch/spawn_semaphore.launch
+++ b/launch/spawn_semaphore.launch
@@ -2,7 +2,7 @@
 <launch>
   <arg name="name"  default="semaphore"/>
   <arg name="model" default="semaphore"/>
-  <arg name="tag"   default="alvar0_negative"/>
+  <arg name="tag"   default="alvar0_neg_1"/>
   <arg name="initial_state"  default="False"/>
   <arg name="x"     default="0.5"/>
   <arg name="y"     default="-0.5"/>
diff --git a/launch/spawn_sign.launch b/launch/spawn_sign.launch
index efedb4536f7f46bdeb1a1b3d65d970ce24963803..49e345644239bf1e507b20bd714a5f7be67a6a57 100644
--- a/launch/spawn_sign.launch
+++ b/launch/spawn_sign.launch
@@ -2,7 +2,7 @@
 <launch>
   <arg name="name"  default="stop"/>
   <arg name="model" default="sign"/>
-  <arg name="tag"   default="alvar1_negative"/>
+  <arg name="tag"   default="alvar1_neg_1"/>
   <arg name="type"  default="stop"/>
   <arg name="x"     default="0.5"/>
   <arg name="y"     default="-0.5"/>
diff --git a/launch/spawn_test.launch b/launch/spawn_test.launch
index 52b6f54b37a4b99a8cb8d81cbed41c28b01671fa..df898a55653d1269cd341de21d0a4d2db48dde98 100644
--- a/launch/spawn_test.launch
+++ b/launch/spawn_test.launch
@@ -61,7 +61,7 @@
   <include file="$(find iri_sign_description)/launch/spawn_sign.launch">
     <arg name="name"  value="unique_loc_sign1"/>
     <arg name="type"  value="world_negative"/>
-    <arg name="tag"   value="alvar3_negative"/>
+    <arg name="tag"   value="alvar3_neg_1"/>
     <arg name="x"  value="0.7"/>
     <arg name="y"  value="0.5"/>
     <arg name="yaw"  value="3.14159"/>