For Greg, who responded to my last post about using the wood float. I was a real nonbeliever at first. I mean, who seriously would think that going back to the plaster (the plaster you labored so hard at to just get to stay on the danged wall) and ripping back over it with a piece of wood could somehow magically make it smooth and crack-free? But somehow it does work. My old-timey plastering guide notes that scouring with the wood float is a necessary step on the process because it "gets the fat back." While I'm not hip to my 1920s-era plastering terminology, I think what it boils down to is this. The skim coat is made of lime putty and sand. Steel finishing trowels have a tendency to (I don't know how or why) separate the two and cause a less-than-strong finished product. The source I have says to go over it once with the steel trowel, just to get it to a modicum of smoothness, then leave it alone. I had a verrrrry difficult time trusting in this logic. After all, wasn't I striving for that beautiful, smooth, clean plaster wall? But by gosh, it actually worked. I put up the skim coat, troweled it over once, and left it.
"Getting the fat back" refers to the wood float's magical ability to push the lime and sand back together and compress the whole shebang into a lovely skim coat. Before I used the float, my walls looked....well, kind of sandy/plastery, not like smooth plaster should look. But the areas in which I used the float, my walls looked super smooth after I was finished. One note of warning: scouring with the wood float is a killer on the wrists! You have to try to maintain an even pressure, all the while scrubbing in circles, but also trying to not create any suction between the float and the plaster (I believe this was my downfall in the lost plaster fiasco....however, I don't want to try it again in order to prove it).
Apparently people who have oodles more experience than me with plaster can actually "polish" a wall to practically a mirror finish using a float. I don't envision that being in my repertoire anytime soon, although I'd sure like to try my hand at it. Virginia Limeworks has a finish that they use in bathroom environments that actually looks almost like a perfect white piece of marble, minus the graining and feathering. It's that smooth and shiny. In person, it's absolutely drop-dead gorgeous. When I had the good fortune to spend a day with Jimmy Price and the VL gang last summer (part of Travis McDonald's Poplar Forest program, which totally rocked!), I practically had to be dragged from their demonstration rooms. I kept stroking this lovely, shiny, smooth, polished surface. It was amazing. Incidentally, if you're ever in the Lynchburg area and are into lime, plaster, and/or museum-quality restoration work, I highly, highly, highly recommend visiting Poplar Forest and giving the guys at VA Limeworks a call. Both experiences are fantabulous. :)
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Very interesting. I was reading about lime putty on a link I found on a UK site and they described lime putty as either being “Fat” or “Lean”. If I remember correctly - and I may not - the “Fatter” the lime putty then the higher content of lime and fewer impurities. Fat lime putty cures a lot slower the lean putty. I wonder if that is where the term “getting the fat back” comes from. Google “fat lean lime putty plaster” and you may find some stuff on it.
Um, OK. Whatever.
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