Yeah, the "budget brand" idea is the problem here. This stuff is one place you can't really cheap out. That grittiness means they used the wrong kind of carbon or filler. It's basically a liquid sandpaper. I just bite the bullet and get the known good stuff from the bike shop. It's cheaper than buying a new seatpost for someone.

28% isn't that high for an old house.

Yeah, that extra minute is everything.