Mixing Solutionb for Pyrocat HD

[patb]

Can anyone help with a mixing procedure for the 100% Potassium Carbonate solution used in part B of Sandy King's Pyrocat-HD formula posted on the Unblinking Eye site. I have been trying to mix 100 grams of Potassium Carbonate into 100ml of distilled water for over an hour now and I can not get the majority of the chemical to stay in solution. As soon as I stop stirring, most of the powder just settles to the bottom of the beaker.
I am new to mixing my own chemeistry from scratch and am going to verify that my measurment was correct (a digital scale indicated I had reached 100grams after about 3.5 tablespoons were added). Mixing was done at room tempeture(70degrees).
Any help would be greatly appreciated.

Pat

 

[Donald Miller]

Your proportions are correct for a 100 % solution. I happen to use sodium carbonate myself even though the formula calls out potassium carbonate. Judging by what Sandy King told me, I will pass along that potassium carbonate dissolves into solution much more rapidly then the sodium carbonate that I use (sodium carbonate reaches saturation sooner then potassium carbonate). Sandy informed me that in light of that inherent tendency that I should use 500 ml of water to the 100 grams of sodium carbonate. And that I should just use five times the amount of solution B in the mixture of the use solution. Perhaps you might benefit from doubling the amount of water in your case and using twice as much "B" as called out. The amount of carbonate in the use solution is the important thing...how it got there is immaterial.

I suspect that your problem is related to the temperature that you are using. Perhaps increasing the temp of your water to 95 degrees would help in dissolving the potassium carbonate. Hope that this helps.

 

[Ole]

Everything became much easier when I bought a magnet stirrer...

But I still don't mix solution "B". I dissolve 7.3 gram Potassium Carbonate in half my final volume of water, then add 10ml of "A" and the rest of the water.

 

[LFGuy]

I second the magnet stirrer! A great piece of equipment to have.

 

[Tom Duffy]

Pat,
I had the same problem, the first time i mixed pyrocat.

First the bad news - at this point, you can stir until the cows come home and the potassium carbonate will never dissolve.

Now the good news - get the potassium carbonate into suspension (stirring rapidly) and pour 10 or 20 ml into your working volume solution (part A developer and water) and it will dissolve readily and work fine.

Going forward, the secret to getting the potassium carbonate to disolve the next time you mix the powder is to slowly (over the course of 5-10 minutes) add the powder into 100ml of moving water. it will dissolve and stay dissolved.

hope this helped.
Tom

 

[David]

I tried an electric stir stick (like for mixing soup). It mixes the stuff post hste. I don't know if the aeration that results is a problem, but it works quickly to dissolve the carbonate.