Ideal Temperature to Make 20ppm Colloidal Silver?

[Mer2112]

Is there an ideal water temperature for making regular 20ppm colloidal silver? I'm using a stirrer during the production.

Thanks,

Eric

[Neofizz]

Temperature determines how much silver oxide will dissolve in the water without falling out of solution. Room temperature (25C) is warm enough for the 20 ppm of silver to stay dissolved in the water.

I make the 20 ppm at room temperature. This enables slower reduction when the reducing agent is added. Slower reduction seems to give a less turbid product. You can see the turbidity under some lighting conditions like shining a flashlight through the solution in dim lighting.

[Mer2112]

When I make 1 liter of 20ppm, I'll heat the water up in the microwave for a couple minutes. It's warm but not hot. I can grab the beaker with my bare hands.

I'll run the batch, add the Karo reducing agent and after letting it stir for a minute or so, toss it in the microwave for 4 minutes.

It's hot/steaming but not boiling and a nice golden "baby shampoo" color.

After that, I'll either cap it with gelatin for internal use and let it cool, or just let it cool enough to put in a storage container.

[FlyingDutchman]

I tend to agree with Neofizz: Research shows that additional heat will cause agglomeration of particles. Enlarged particle size may cause a red shift, causing the colloid to look more golden at lower ppm. My 20 ppm is always bright yellow. I generally produce at room temperature to 35 °C maximum. Only reduction agents like sodium citrate need higher temperatures.