diff --git a/Makefile b/Makefile
index 51fb513..bca7fc7 100644
--- a/Makefile
+++ b/Makefile
@@ -12,9 +12,12 @@ export SBSFILES = $(wildcard $(SBS_DIR)/*.sbs)
 export SBSARDESTINATION = $(subst $(SBS_DIR)/, $(SBSAR_DIR)/, $(SBSFILES))
 export SBSARFILES = $(SBSARDESTINATION:.sbs=.sbsar)
 
+# existing texturesets list
+export TEXTURES := $(wildcard $(TEXTURESET_FOLDER)/*)
+
 ### RECIPE PART ###
 
-all : previews subformats
+all : previews subformats del_obsolete
 
 previews: $(SBSARFILES)
 	$(MAKE) -f Makefile_previews all
@@ -22,12 +25,32 @@ previews: $(SBSARFILES)
 subformats: $(SBSARFILES)
 	$(MAKE) -f Makefile_subformats all
 
+del_obsolete: $(SBS_DIR)
+	@ for material in $(TEXTURES); do \
+	rootname=$$(echo $$material | sed -r 's|$(TEXTURESET_FOLDER)/(.*)_.*|\1|');\
+	sbs_name=$(SBS_DIR)/$$rootname.sbs ;\
+	if [ ! -f $$sbs_name ] ;\
+	then echo "CLEANUP : The corresponding $$sbs_name doesn’t exist any more, deleting the corresponding obsolete files :" ;\
+	rm -Rf $(SBSAR_DIR)/$$rootname.sbsar ;\
+	echo " -"$(SBSAR_DIR)/$$rootname.sbsar ;\
+	rm -Rf $(PNG1024_DIR)/$$(basename $$material)* ;\
+	echo " -"$(PNG1024_DIR)/$$(basename $$material)* ;\
+	rm -Rf $(PNG512_DIR)/$$(basename $$material)* ;\
+	echo " -"$(PNG512_DIR)/$$(basename $$material)* ;\
+	rm -Rf $(PNG256_DIR)/$$(basename $$material)* ;\
+	echo " -"$(PNG256_DIR)/$$(basename $$material)* ;\
+	rm -Rf $(TEXTURESET_FOLDER)/$$(basename $$material) ;\
+	echo " -"$(TEXTURESET_FOLDER)/$$(basename $$material) ;\
+	rm -Rf $(PREVIEW_FOLDER)/$$(basename $$material)* ;\
+	echo " -"$(PREVIEW_FOLDER)/$$(basename $$material)* ;\
+	fi ;\
+	done
+
 export: $(SBSARFILES)
 	$(MAKE) -f Makefile_export all
 
 # Recipe to make sbsar, its main PNG files and its preset textureset file
 $(SBSAR_DIR)/%.sbsar: $(SBS_DIR)/%.sbs
-	@ echo $$(basename $@ ".sbsar")
 	@ echo "Processing" $< "->" $@
 	@ mkdir -p $(SBSAR_DIR)
 	@ $(MAKESBSAR) --output-path $(SBSAR_DIR) $<
@@ -35,9 +58,9 @@ $(SBSAR_DIR)/%.sbsar: $(SBS_DIR)/%.sbs
 # There is a png imageset for each preset of a base texture
 # All png are stored in a png_1024 folder
 	@ mkdir -p $(PNG1024_DIR)
-	@ echo "Building 1024 png imageset(s) from presets of" $@
-# Get all presets from this base material
+# Get all presets for the graph
 	@ $(eval PRESETLIST=`$(GETPRESET) --input $< | grep PRESET | sed -r 's/PRESET "(.*)"/\1/g'`)
+# Get graph outputs list
 	@ declare -i graphcount=0 ;\
 	output_list="" ;\
 	for line in $$($(GETOUTPUT) $<) ; do \
@@ -51,12 +74,18 @@ $(SBSAR_DIR)/%.sbsar: $(SBS_DIR)/%.sbs
 	else : ;\
 	fi ;\
 	done;\
-	echo "output_list :"$$output_list;\
+	echo " - Graph output_list :"$$output_list;\
+	echo "Building 1024 png imageset(s) from presets of" $@ ;\
 	pngfiles="";\
-	material=$$(basename $@ ".sbsar");\
-	echo "material :"$$material;\
 	for preset in $(PRESETLIST) ; do \
 	echo "- Preset" $$preset; \
+	material=$$(basename -s .sbsar $@);\
+	echo "material :"$$material;\
+	obsolete="$${material}_$${preset}" ;\
+	echo "Cleaning old entries from the material : $$obsolete" ;\
+	rm -Rf $(PNG1024_DIR)/$$obsolete* ;\
+	rm -Rf $(PNG512_DIR)/$$obsolete* ;\
+	rm -Rf $(PNG256_DIR)/$$obsolete* ;\
 	listitem="";\
 	for item in $$output_list;\
 	do itemfull="$(PNG1024_DIR)/$${material}_$${preset}_$${item}.png";\
@@ -64,7 +93,7 @@ $(SBSAR_DIR)/%.sbsar: $(SBS_DIR)/%.sbs
 	done;\
 	echo "listitem :"$$listitem;\
 	mkdir --parents $(TEXTURESET_FOLDER);\
-	echo $$listitem > $(TEXTURESET_FOLDER)/$$(basename $@ ".sbsar")_$$preset;\
+	echo $$listitem > $(TEXTURESET_FOLDER)/$$(basename -s .sbsar $@)_$$preset;\
 	$(SBSRENDER) render $@ --use-preset $$preset --output-name {inputGraphUrl}\_$$preset\_{outputNodeName} --set-value \$$outputsize@10,10# --output-path $(PNG1024_DIR); \
 	done;\