Trisodium phosphate
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Trisodium_phosphate_hydrate.jpg
Trisodium phosphate, available at most hardware stores in white powder form, is a cleaning agent and degreaser, commonly used to prepare surfaces for painting (household), sold as 'TSP'. It can also be called trisodium orthophosphate and has the chemical formula Na3PO4. It is a highly water-soluble ionic salt. Solutions of it dissolved in water have an alkaline pH.
It can also be found as a food additive: buffer agent, emulsifier, nutrition enlargement agent and metal-chelating agent. In these uses it may be known as simply sodium phosphate.
The CAS number for Trisodium Phosphate is 7601-54-9. The UN number is 1178 (http://www.inchem.org/documents/icsc/icsc/eics1178.htm).
TSP for cleaning
Similar chemicals were once common in laundry and dishwashing detergents, but the phosphate, being a fertilizer, would cause algal blooms in the bodies of water that the drains led to. In the early 1970's the use of phosphate-containing products was limited. Now products sold as [TSP Substitute (http://www.dap.com/retail/retail_detail.cfm?catid=8&subcatid=105&prodhdrid=319)], containing 80–90% Sodium carbonate, are promoted as a direct substitute.
Cleaning products labeled as TSP may contain other ingredients as well, and may in fact be [less than half (http://www.dap.com/msds/79400.pdf)] TSP. So even "regular" TSP found at the hardware store may be half TSP and half "TSP substitute". Savogran's brand actually contains (http://www.savogran.com/Information/TSP_MS.pdf) 80% trisodium phosphate dodecahydrate.
So, recipes for cleaning solutions that call for a quantity of TSP may vary considerably in strength depending on the brand of TSP product used as an ingredient! So always test the actual strength and effects of a product even if you've used TSP before in the same situation.
Although it is the active ingredient in at least one toilet bowl cleaning tablet, TSP is generally not good for cleaning bathrooms, because it can oxidize metal.
TSP is commonly used after cleaning with mineral spirits in order to then clean up all the mineral spirits. TSP may be used with household chlorine bleach in the same solution, and this is particularly good for removing mildew from wood. The TSP alone can cause dark stains on redwood, and bleach prevents it. In fact, the California Redwood Association recomends TSP + bleach (http://www.calredwood.org/ref/pdf/colorest.pdf)] as a first step (prior to oxalic acid) in removing dark stains caused by extractive bleeding.
Use as a Ph Buffer
A mixture of monosodium phosphate and trisodium phosphate is used as a phosphate buffer: [1] (http://members.nuvox.net/~on.jwclymer/phos.html)
External Links
- TSP... CLEANING FOR THE BIG DOGS!! (http://www.naturalhandyman.com/iip/infxtra/inftsp.shtm)
- TSP for sale at the Chemistry Store (http://www.chemistrystore.com/trisodium_phosphate.htm)
- Safety data from IPCS INCHEM (http://www.inchem.org/documents/icsc/icsc/eics1178.htm)
- PubChem Substance Summary (http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=166757)