Citat from SB forum

"Hi. I've got some thoughts from my woody background. With timber we are taught that the best surface to bond to is a cleanly cut unabraded surface. The logic goes something like this. A surface prepared with a sharp edge cutting tool, like a chisel or planner, has excellent surface integrity - undamaged wood fibres, clear open pores and an unoxidised surface.
Therefore the worst possible surface to bond to is an abraded surface that has being exposed to the air for a long time. The problem with sanding the surface comes from the tendency of the sanding medium to partial remove long timber fibres leaving the surface a mess of partial unattached fibres that prevent the adhesive reaching the undamaged timber. These fibres then break free when a load is applied to the bond causing the whole join to fail.
I'd assume that a blunt planner creates a similar problem in that the surface of the timber is crushed reducing its ability to absorb the adhesive and then breaking away once a load is applied.
Having said that when I've used UHMWPE side walls I have abraded these once attached and profiled, effectively sanding the core along a 80ish mm strip on each side.
For my money the best bet is to use a sharp planner/router or if you must sand use the coarsest paper you can without wrecking the core and don't store you cores for long.
Chris
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