diff --git a/simgear/scene/material/Effect.cxx b/simgear/scene/material/Effect.cxx
index bfbc1412..70792a7a 100644
--- a/simgear/scene/material/Effect.cxx
+++ b/simgear/scene/material/Effect.cxx
@@ -89,36 +89,17 @@ using namespace osgUtil;
 
 using namespace effect;
 
-class UniformFactoryImpl {
-public:
-    ref_ptr<Uniform> getUniform( Effect * effect, 
-                                 const string & name, 
-                                 Uniform::Type uniformType, 
-                                 SGConstPropertyNode_ptr valProp, 
-                                 const SGReaderWriterOptions* options );
-    void updateListeners( SGPropertyNode* propRoot );
-    void addListener(DeferredPropertyListener* listener);
-private:
-    // Default names for vector property components
-    static const char* vec3Names[];
-    static const char* vec4Names[];
-
-    SGMutex _mutex;
-
-    typedef boost::tuple<std::string, Uniform::Type, std::string, std::string> UniformCacheKey;
-    typedef boost::tuple<ref_ptr<Uniform>, SGPropertyChangeListener*> UniformCacheValue;
-    std::map<UniformCacheKey,ref_ptr<Uniform> > uniformCache;
-
-    typedef std::queue<DeferredPropertyListener*> DeferredListenerList;
-    DeferredListenerList deferredListenerList;
-};
-
 const char* UniformFactoryImpl::vec3Names[] = {"x", "y", "z"};
 const char* UniformFactoryImpl::vec4Names[] = {"x", "y", "z", "w"};
 
-ref_ptr<Uniform> UniformFactoryImpl::getUniform( Effect * effect, 
-                                 const string & name, 
-                                 Uniform::Type uniformType, 
+void UniformFactoryImpl::reset()
+{
+  uniformCache.clear();
+}
+
+ref_ptr<Uniform> UniformFactoryImpl::getUniform( Effect * effect,
+                                 const string & name,
+                                 Uniform::Type uniformType,
                                  SGConstPropertyNode_ptr valProp,
                                  const SGReaderWriterOptions* options )
 {
@@ -223,8 +204,6 @@ void UniformFactoryImpl::updateListeners( SGPropertyNode* propRoot )
 	}
 }
 
-typedef Singleton<UniformFactoryImpl> UniformFactory;
-
 
 Effect::Effect()
     : _cache(0), _isRealized(false)
diff --git a/simgear/scene/material/Effect.hxx b/simgear/scene/material/Effect.hxx
index 84a25222..56a84769 100644
--- a/simgear/scene/material/Effect.hxx
+++ b/simgear/scene/material/Effect.hxx
@@ -20,8 +20,10 @@
 #include <vector>
 #include <string>
 #include <unordered_map>
+#include <queue>
 
 #include <boost/functional/hash.hpp>
+#include <boost/tuple/tuple.hpp>
 
 #include <osg/Object>
 #include <osg/observer_ptr>
@@ -29,6 +31,9 @@
 
 #include <simgear/props/props.hxx>
 #include <simgear/scene/util/UpdateOnceCallback.hxx>
+#include <simgear/threads/SGThread.hxx>
+#include <simgear/threads/SGGuard.hxx>
+#include <simgear/structure/Singleton.hxx>
 
 namespace osg
 {
@@ -48,6 +53,9 @@ class Technique;
 class Effect;
 class SGReaderWriterOptions;
 
+using namespace osg;
+using namespace std;
+
 /**
  * Object to be initialized at some point after an effect -- and its
  * containing effect geode -- are hooked into the scene graph. Some
@@ -168,5 +176,33 @@ void mergePropertyTrees(SGPropertyNode* resultNode,
                         const SGPropertyNode* left,
                         const SGPropertyNode* right);
 }
+
+class UniformFactoryImpl {
+public:
+    ref_ptr<Uniform> getUniform( Effect * effect,
+                                 const string & name,
+                                 Uniform::Type uniformType,
+                                 SGConstPropertyNode_ptr valProp,
+                                 const SGReaderWriterOptions* options );
+    void updateListeners( SGPropertyNode* propRoot );
+    void addListener(DeferredPropertyListener* listener);
+    void reset();
+private:
+    // Default names for vector property components
+    static const char* vec3Names[];
+    static const char* vec4Names[];
+
+    SGMutex _mutex;
+
+    typedef boost::tuple<std::string, Uniform::Type, std::string, std::string> UniformCacheKey;
+    typedef boost::tuple<ref_ptr<Uniform>, SGPropertyChangeListener*> UniformCacheValue;
+    std::map<UniformCacheKey,ref_ptr<Uniform> > uniformCache;
+
+    typedef std::queue<DeferredPropertyListener*> DeferredListenerList;
+    DeferredListenerList deferredListenerList;
+};
+
+typedef Singleton<UniformFactoryImpl> UniformFactory;
+
 }
 #endif
diff --git a/simgear/scene/material/makeEffect.cxx b/simgear/scene/material/makeEffect.cxx
index 628d7143..cfbb87af 100644
--- a/simgear/scene/material/makeEffect.cxx
+++ b/simgear/scene/material/makeEffect.cxx
@@ -278,8 +278,10 @@ Effect* makeEffect(SGPropertyNode* prop,
 
 void clearEffectCache()
 {
+    SG_LOG(SG_INPUT, SG_DEBUG, "clearEffectCache called");
     OpenThreads::ScopedLock<OpenThreads::ReentrantMutex> lock(effectMutex);
     effectMap.clear();
+    UniformFactory::instance()->reset();
 }
 
 }