Ethiopian opal sodium silicate (water g;ass) treatment

I seriously doubt the treatment will stop the crazing/cracking for a very simple reason.

Let's start with how opal forms. Opal starts out as a silica rick solution. As the silica molecules start to attract towards each other, water gets squeezed out. When a water content of 3-21% remains, the result is opal. If the water content drops below 3% then the silica starts to crystalize in to some form of chalcedony.

So why does the opal have a tendency to crack and craze and the chalcedony does not once formed? Simple. The chalcedony is a true solid as where the opal is not. Opal is actually a solid gel. The reason it tends to crack is because as a gel it has to have time to stabilize as it loses its water. The higher the water content to start with, the greater the risk. As the opal loses water the gel has to restructure itself in to a stable form. If the water loss is faster than the gel has time to restructure, the the result is cracking.

Thus is why opal that is suddenly brought from deep under to the surface suddenly, such as from mining, earthquake thrusts, being exposed from floods, etc. are very unstable and tend to crack. The gel is suddenly drying too fast not leaving time to stabilize. In the other hand, I find opal all the time here in Nevada that is very stable. A lot of the opal was near the surface, but not on the surface so it had time to slowly drop its water as the soil above it was enough to hod some moisture and allow the opal to slowly lose water content and stabilize before finally coming to the surface or being dug out from a few inches below the surface.

People will sometimes try to mimic this to stabilize opal. If some opal is brought to the surface from mining, it can be very slowly dried to allow it to stabilize by slowly restructuring. This is often done by putting the opal in a zip lock bag, or preferably 2 bags, with a wet paper towel. The opal in the bag is then set in a dark, temperature stable location and the water in the bag will slowly dissipate allowing the opal to acclimate and restructure to a stable structure. Again, the higher the initial water content the more unstable the opal will be, so this does not work 100% of the time, although even slower loss of water from the bag may help stabilize some of the higher water content opal.

The reason I doubt the sodium silicate polymerization will work is because you are not trying to fill cracks and voids in a true solid like a chalcedony. The opal again is a gel and thus the molecules are still in movement. This would be like pouring cement between gaps in wet mud in an attempt to stop the mud from cracking as it dries. Not going to work.