Hot off the test bench so please excuse the lack of spreadsheet organization! Two glues and varying glue methods were used to compare the adhesion strength of key tops with fronts to the wood keystick. Eight keys were from the same piano and the top and front key wood was planed to create a clean surface. Glue was applied with a half inch flat brush. Only enough glue was used that would result in minor squeeze-out. A fine, broad bladed knife was used to remove the tops/fronts, after drying, to test adhesion. PVC-E: Straight from the jar, no glue sizing of wood, no clamping, 12 hour dry time - both top and front adhered well and moderate effort was needed to remove the key top and front. Equal wood/glue evident on both surfaces. No sizing, clamped 12 hours in Oslund key clamp - key top and front were easy to remove and showed very little glue remaining in joint. Glue sized, no clamping, 12 hour dry time - key top and front required even less effort than the above to remove. Glue had not adhered to sized surface and remained with keytop/front. Sized and clamped in Oslund key clamp, 12 hour dry time in clamp - Best adhesion although only slightly more difficult to remove than no sizing no clamping. Shifting of top in clamp required extra diligence. Mike's Euro Glue (Meuro): Straight from bottle, no sizng, no clamping, 12 hour dry time - moderate effort needed to remove top and front. Adequate adhesion. No sizing, clamped in Oslund for 12 hours - same as above. Good adhesion, moderate effort needed for removal. Glue sized, no clamping, 12 hour dry time - same result as with PVC-E. Poor adhesion leaving glue on equally on both surfaces. Glue sized, clamped in Oslund 12 hours - moderate effort required for removal, good adhesion. Didn't shift as much as PVC-E. Some comments: The Oslund clamp is difficult to use with keytops that have fronts attached. However, once the system is figured out and the appropriate shims are at the ready, it will work and will apply clamping to both the top and the front simultaneously. A bit tricky. Both glues, used appropriately, seem to work fine. I have, in the past, tried contact cement but I hate the vapors. I have also experimented with keytop dissolved in acetone as a glue. Much practice with timing and neatness is needed with the acetone mixture and it will easily destroy the plastic if you get the least bit where it's not wanted. Also, it is far too strong a joint making future removal for repairs/replacement a nightmare. Personally, I prefer PVC-E and no glue sizing and no clamping. Each top w/front is aligned and is 'stuck' with an even finger pressure moving from front (head) to back (tail). Alignment is re-checked and the key is set aside to dry. Haven't had a failed joint. I am sure that Mike has seen similar results with his glue and his method. (Yes, I'm keeping my Oslund clamp!) Debbie L. Rockport, MA -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100101/ecc89cbb/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: IMAG1404.JPG Type: image/jpeg Size: 188415 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100101/ecc89cbb/attachment-0001.jpeg>
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