With chanter reeds, does anyone happen to know what might cause the first octave F# and G to become extremely sensitive to pressure, sharpening with less and flattening with more? Is there a tweak to eliminate this or reduce/prevent it in future reeds? Has a section of the scrape been overthinned? Thanks for your help!
If your reed was OK before, it can’t be the scrape. First, check that the keys on the chanter are sealing properly (staunch stopping, as Ennis put it). Leaky keys cause all sorts of woe. If keys are OK, check that the reed hasn’t sprung a leak and that it is well and firmly seated in the chanter. If the former, lightly wrap some teflon tape around the reed and see if that helps. If it’s the scrape (your back D should be sinking), see a reed surgeon. Good luck!
I get this sometimes - where with insufficient pressure the f and g play sharper, and then sink to the correct pitch with more air. If it’s like this then you can - back D situation dependant of course - just weaken the reed a little bit by scraping - for example you could scrape the edges a bit.
More annoying is the related but altogether less helpful situation where the notes are sinking too far and playing flat as you pile on some pressure. In that case i usually try and mess around with the bridle - probably place it higher up the reed which i consider to be a bit like ‘un-scraping’ a little by way of adding stiffness. Of course if overall pitch is a bit flat you could always stiffen the reed a bit by lopping a little off the tip.