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I've had a problem with weight painting a seamed mesh with textures and particle systems applied. Using Blender 2.79. I found that, once I switch to weight paint mode from Object mode, the mesh pattern shows up as if Wire and Draw all edges were ticked but greyed out - and I can't paint weights at all on the mesh surface. After a day's work of getting nowhere, I discovered a workaround. Which was to hover over the mesh and pressing L as if selecting a seamed section in Edit mode. Obviously the seaming was creating problems but what's the answer? Should I clear the seams before rigging or is there a better way of dealing with this?