What could be harder than measuring out 100ml of T-max developer in a small graduate each time you need it. The stock solution seems to keep for a long, long time. Its high viscosity makes it very easy to pour to the exact measure, even when pouring from the gallon jug. If I were to 'home brew' a developer, I'd copy that.
Moved from another thread.
My question is: How can we guarantee that the powder stays mixed well? I guess the user could shake the jar before measuring-out some powder, but I'm still not sure that coarse and fine powders would be mixed uniformly.
Depends on what kind. If it is borax and ascorbic acid, there is no problem.
Also, acid touching alkali (as powders) can cause problems
I think the packaging of XTOL was decided so as to minimize the impact of small errors in metering process as well as potential risk of ingredients segregation.
XTOL fixed the problem by having two packets.
One thing I can tell you is that it is a LOT easier to get better uniform mixture in a small mixer (say a kilogram or less of the powder developer) than a large mixer producing 100kg or a metric ton.
The trickiest part is to mix phenidone (very fine sticky powder used in such a small quantity) uniformly first. Then the rest of the problem is a lot easier. The best way to mix is to use a slow random motion to mix in a vessel with lots of free room. This is exactly what industrial mixers can’t do.
I tried mixing 1 part phenidone with 9 parts ascorbic acid, in a small jar. Both are fine powders, and they mix together well. This gives me a 10% powder-mixture of phenidone that's easier to weigh. For example, I weigh out 1 g of this mixture to get 0.1 g of phenidone. Just to be sure, I shake before each use. Repeatability appears to be fine with this powder-mixture.
Originally Posted by Ryuji
I like your powder-idea, and I suspect that you can make it work, if my test above is any example. Be sure to have somebody test it in humid Florida and dry Arizona. For me, shaking two jars for a few seconds before measuring out powders is no problem. BTW, do you of ways to make phenidone/dimezone dissolve faster?
Don't tell me this is different from what you learned from old books, but I do know of a good way. Dissolve all alkali in water first. Then add just a bit of sulfite and a bit of ascorbate. Dissolve any organic compound (Phenidone, Dimezone, benzotriazole) and then add the rest of the ingredients. That is, those organics will dissolve easily in alkaline solution of a low salt concentration.
Originally Posted by albada
I remember some postings awhile ago on another thread about measuring from mixtures. But I can't find the postings even with Advanced Search. Anyway, I think Ron Mowrey (PE) posted some cautions based on his experiences at Kodak. Hopefully he'll chime-in on this.
Originally Posted by Kirk Keyes
But I remember reading web pages about it, and seeing diagrams of different ways that particles of differing weights and sizes can sort themselves in a container. Perhaps you'll be okay if your chemicals have similar densities, because neither will try to float above or sink below the other. I just wish I could give you a link to that thread...
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Because of the political behavior started by some, there is an agreement that he shall not post on my thread and vice versa. We are not supposed to mention each other’s work.
Originally Posted by albada
That sounds right. But the way ingredients segregate depends a lot on the construction of the mixer and revolution speed. Although this is not a high tech or anything, there is more industrial know-how in this area now than just a couple of decades ago.
But I remember reading web pages about it, and seeing diagrams of different ways that particles of differing weights and sizes can sort themselves in a container.
The key is that you stir the vessel slowly and randomly each time you take the portion you want.
Perhaps you'll be okay if your chemicals have similar densities, because neither will try to float above or sink below the other.
I also thought about making a paste. Like toothpaste. You decide like take 10cm per liter of water to make working developer. This is doable but too much work to package the stuff!
Due to globalization I think we have a couple of disused toothpaste packing machine setups sitting here.............!
And I think you just stole "the other guys" thunder, I'm about to wrap up the festive seasons playtime with tea, ascorbate and soda, and will be hunting high and low for Vitamine B to play with! Thanx!
Your powder mix may be similar to the powder Fomadon Excel:
I have a number of 1L packs of this years past the expiry date that still work OK.
It is not known how Foma mix the powder but if you could match their mixing your powder should keep well.
If not you could add a little metabisulfite to reduce the pH and oxidation rate of any damp ascorbate.
I think it’s more important to keep the powder in environment free of excess moisture. I’d use vacuum container anyway.
Originally Posted by Alan Johnson
I’d rather not use metabisulfite in this. Zat stuff stinks. As I said before, I’d rather use a water soluble polymer and sorbitol to “dilute” Phenidone and then make the fine powder stick to other ingredients used in more bulk quantities.
Yeah if I were to sell the products I’d rather make fancy tablets or paste in tube. But at this point and time it is commercially inviable. Unless... someone wants to start a kickstarter project and raise some money for the project haha.
But then I thought about it. The developer stabilizer I’m going to use is not a compound that’s commonly available. When Silvergrain products were sold, I actually prepared that stuff in my lab and shipped it to the factory. So publishing the formula is also of little value... unless I somehow make this stabilizer available.