Author Topic: question about "stability" of colloid particles  (Read 4102 times)

vratoemba

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question about "stability" of colloid particles
« on: February 09, 2012, 07:54:18 PM »
people talk about the "shelf life" of collodial gold.
and also about the "stability" of the gold particles.

what happens when collodial gold becomes "unstable"?
and what happens to the particles?

for example: if I would just put some collodial gold on the heater, and let the water slowly evaporate, what would happen with te particles?
would I have any gold-residu left?


Offline kephra

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Re: question about "stability" of colloid particles
« Reply #1 on: February 11, 2012, 04:34:49 PM »
Over time, some types of colloidal gold may show signs of the gold falling out.  You may see black residue on the bottom of the bottle.  When this happens, the colloidal gold has become weaker.  But really there is no 'shelf life' per se for gold. 

If a colloid is stable, it means that the particles will not change in size, or chemical makeup.

When you try to evaporate gold or any other colloid, you are increasing the ppm of the colloid, and you are decreasing the volume.  This forces the nanoparticles closer together, and if they are forced close enough together they will combine to make larger particles.  This happens much faster if there is no stabilizer in the colloid.  In the end, you will still have all of the gold, but the particles will be larger, and may not reconstitute if you add back the water.

There is one other issue with 'shelf life', and that is sterility.  Colloidal gold has no antibacterial properties, so it is possible for it to grow molds and bacteria. 
There is the unknown and the unknowable.  It's a wise man who knows the difference.

vratoemba

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Re: question about "stability" of colloid particles
« Reply #2 on: February 12, 2012, 09:37:17 AM »
thankx for the reply!

that is what I wanted to know!


tinhorn

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Re: question about "stability" of colloid particles
« Reply #3 on: January 25, 2015, 02:43:12 PM »
When you try to evaporate gold or any other colloid, you are increasing the ppm of the colloid, and you are decreasing the volume.  This forces the nanoparticles closer together, and if they are forced close enough together they will combine to make larger particles.

I've been making a 40ppm batch each day for the past two weeks.  I know the recipe for 250ppm has been posted.  As a point of curiosity, what would the highest practical concentration be, while avoiding the risk of creating those larger particles mentioned above?

milad

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Re: question about "stability" of colloid particles
« Reply #4 on: July 11, 2015, 09:19:13 AM »
does the sequence or time of adding ingredients matter for higher stability?

Offline kephra

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Re: question about "stability" of colloid particles
« Reply #5 on: July 11, 2015, 11:12:18 AM »
That aspect is untested, but probably not.
There is the unknown and the unknowable.  It's a wise man who knows the difference.