[smithgabriel]

I have some tungstic acid that is yellow, and when I use a spatula to push down on the powder or move it around, it turns a blue color.  I know that there are tungsten blue oxides, but has anyone ever seen tungstic acid change color from a stainless steel spatula?  Is this reversible?

[Radu]

 Are you sure it's a stainless steel spatula? What if it's a Zn based alloy? W⁵⁺ is fairly blue, so your spatula's metal may reduce WO₃*nH₂O

[Arkcon]

I don't really understand the chemistry at work here, although Radu: seems to be on the right track -- the spatula may have reduced the sample, either because of what it was made of, or.  You really shouldn't use a metal spatula with reactive reagents.  You can try a disposable plastic spatula.  My favorite thing is to cut the bulb of a polypropylene dropper in half.  That give me a spoon that I know has never touched another reagent ... because it was never a spoon in the first place.

[smithgabriel]

Thanks for the info.  I did find an old paper that describes the dry testing for tungstic acid using a spatula.  It involves rubbing a spatula onto the Tungstic acid sample and looking for a blue/grey color that indicates reduction.