Well, like I said earlier, according to "teh interwebz" (therefore it must be true) it's 70% Sodium Percarbonate, 30% Sodium Metasilicate. Therefore the 70/30 of Oxy to TSP/90 seems to be the ACTUAL formula (Since Oxy's 100% (ish) sodium percarbonate, and the Red Devil TSP/90 is 100% (ish) Sodium Metasilicate.)
Anyways - mason jar test came out fine. Mason jar containing near boiling water, added a tablespoon of the homemade PBW blend, shook the everloving ****e out of it, and let it sit until this morning. Made sure everything was dissolved, and there were no issues (that I can see) with the glass. So screw it, I'm using it from here on in.
Even if it's just for cleaning out the keggles, etc. and I use PBW for the glass, it still stretches PBW a lot further than normal.
Originally Posted by phrogpilot73
Just out of curiosity, did you do your ratios by weight or by volume? I'm thinking this will save me some money...
I measured by weight. I used a 16oz bag of the TSP/90, and using some good ol' math calculated that I needed about 37oz of Oxy to hit the 70/30 ratio. Poured both into to a large container where I mixed 'em thoroughly for a minute or so. I wore a facemask (just one of the cheaper paper ones you use when painting, since there was one right there on my workbench as I was doing this) since it did throw up some dust during the mixing process, and I'd rather not have it in my lungs. Then poured the mixture into a container, along with the handy Oxy scoop, and will be using it for my next brewday.
In terms of savings, it's pretty damned impressive. Even if you were doing this from scratch - a 14lb box of Oxy from Costco is about $16, which if you mix with 6lbs of TSP/90 (they do sell 4lb bags) at a cost of around $20, you end up with 20lbs of "homemade" PBW for $36.
I pay $20 for a 4lb jar of PBW, so to get the same amount, it'd set me back $100.
The caution would be to pay attention to your TSP substitute. From my research, Red Devil TSP/90 is the ONLY one I could find that's 100% sodium metasilicate. The stuff carried by all the local hardware stores like Osh, Home Depot, Lowes, and even some of the Ace Hardware shops, were different brands, and looking up their MSDS gave different ingredients. I'm sure you can use one of them in a pinch, but YMMV.
And also, I'd be sure and do what I did if you mix a batch of this up - do a couple of test runs on some glass items you don't care about.