diff --git a/examples/demos/conservation.py b/examples/demos/conservation.py
index b2e206c126e32543bc297508aa6bca5740b4b7f4..e4a254448462f41a68c15ff048fa6dc67dfe09ab 100644
--- a/examples/demos/conservation.py
+++ b/examples/demos/conservation.py
@@ -13,8 +13,6 @@ aln.SetSequenceOffset(0, 1)
 # First we set all properties to zero, then let alg.Conservation assign the
 # conservation scores to the residues
 #-------------------------------------------------------------------------------
-for r in m.residues:
-  r.SetFloatProp('cons', 0)
 alg.Conservation(aln)
 
 #-------------------------------------------------------------------------------
diff --git a/modules/gfx/doc/entity.rst b/modules/gfx/doc/entity.rst
index 4ebe5f7d8d1b1324d54cbad1e655a49639453ecb..42fa5e38b16fe4c2ba300ed85c0aafcb08787810 100644
--- a/modules/gfx/doc/entity.rst
+++ b/modules/gfx/doc/entity.rst
@@ -196,6 +196,9 @@ Entity API Reference
     the built-in properties is identical to the properties available in 
     :doc:`query language <../mol/base/query>`.
     
+    In case a generic property is undefined for a certain element, the property 
+    the value of min is used for that element.
+    
     :param prop: The name of the numeric property
     :type  prop: str
     :param color1: Color corresponding to min value
diff --git a/modules/gfx/src/impl/entity_renderer.hh b/modules/gfx/src/impl/entity_renderer.hh
index 28a932abfe81aa3ff3fd47bbee41caf91200b980..b3e47c0123ed60c219db51ed11a0ecc38cab6807 100644
--- a/modules/gfx/src/impl/entity_renderer.hh
+++ b/modules/gfx/src/impl/entity_renderer.hh
@@ -57,7 +57,7 @@ namespace ost { namespace gfx { namespace impl {
 
 typedef enum {
   DIRTY_VIEW   =1,
-  DIRTY_VA     =2,
+  DIRTY_VA     =2
 } DirtyFlag;
 
 typedef char DirtyFlags;
@@ -204,14 +204,14 @@ struct UniformGetCol {
 };
 
 struct GradientLevelGetCol {
-  GradientLevelGetCol(const GradientLevelColorOp& op):property_(op.GetProperty()),
+  GradientLevelGetCol(const GradientLevelColorOp& op): property_(op.GetProperty()),
       epm_(property_, op.GetLevel()),
       gradient_(op.GetGradient()),
       minv_(op.GetMinV()),
       maxv_(op.GetMaxV()){}
   Color ColorOfAtom(mol::AtomHandle& atom) const{
     try{
-      float n=Normalize(epm_.Get(atom), minv_, maxv_);
+      float n=Normalize(epm_.Get(atom, minv_), minv_, maxv_);
       return gradient_.GetColorAt(n);
     }catch(std::exception&){
       LOGN_DEBUG("property " << property_ << " not found");
diff --git a/modules/gfx/src/impl/trace_renderer_base.cc b/modules/gfx/src/impl/trace_renderer_base.cc
index 46084a880b330f86fe618c86cb88e4eb315bc3d1..6a49d7c1660b0863c84fb0caf82a38272006bd87 100644
--- a/modules/gfx/src/impl/trace_renderer_base.cc
+++ b/modules/gfx/src/impl/trace_renderer_base.cc
@@ -34,7 +34,9 @@ void set_node_entry_color(NodeEntry& e, ColorMask mask,
 }
 
 template <typename T1>
-inline void apply_color_op(TraceRendererBase* rend, TraceSubset& trace_subset, T1 get_col, const ColorOp& op)
+inline void apply_color_op(TraceRendererBase* rend, 
+                           TraceSubset& trace_subset, T1 get_col, 
+                           const ColorOp& op)
 {
   rend->UpdateViews();
   ColorMask mask = op.GetMask();
diff --git a/modules/gfx/src/surface.cc b/modules/gfx/src/surface.cc
index dbf740077238e34c36356fe58e35cdeb473d8b51..00ee954a959809f860c2f17cb70bc705df6dc6b8 100644
--- a/modules/gfx/src/surface.cc
+++ b/modules/gfx/src/surface.cc
@@ -311,7 +311,8 @@ void Surface::Apply(const gfx::GradientLevelColorOp& op, bool store){
   for(VMap::const_iterator it=vmap_.begin();it!=vmap_.end();++it) {
 	mol::AtomHandle ah = sh_.GetVertex(it->first).atom;
 	if(ah.IsValid()) {
-	  va_.SetColor(it->second,gradient.GetColorAt(normalize(epm.Get(ah),minv,maxv)));
+	  va_.SetColor(it->second,gradient.GetColorAt(normalize(epm.Get(ah, minv),
+	                                              minv,maxv)));
 	}
   }
   FlagRefresh();
diff --git a/modules/mol/base/src/entity_view.cc b/modules/mol/base/src/entity_view.cc
index 6be3145f35ac93cdfe8c4432a6978098b395aa42..d81d02d986e7651354fadde6feeef814b2a4958f 100644
--- a/modules/mol/base/src/entity_view.cc
+++ b/modules/mol/base/src/entity_view.cc
@@ -688,9 +688,14 @@ std::pair<Real,Real> EntityView::GetMinMax(const String& prop,
   Real min_v=std::numeric_limits<Real>::max();
   Real max_v=-std::numeric_limits<Real>::max();  
   for(AtomViewIter it=AtomsBegin(); it!=this->AtomsEnd(); ++it) {
-    Real v=epm.Get(*it);
-    max_v=std::max(v, max_v);
-    min_v=std::min(v, min_v);
+    try {
+      Real v=epm.Get(*it);
+      max_v=std::max(v, max_v);
+      min_v=std::min(v, min_v);      
+    } catch(...) {
+      // do nothing in case of missing property
+      continue;
+    }
   }
   return std::make_pair(min_v,max_v);
 }