Glass recommendations

Just looking for a piece of at least 6 by 6 inch glass that I can put ontop of my riser so I can observe the flame.
Anything I can purchase off Amazon or elsewhere?  Maybe some sort of glass tile.

I found a 3.5" by 3.5" Fused Silica plate on Amazon https://www.amazon.com/dp/B00OZXNZDM
If you want bigger pieces, you may have to ask the manufacturer.

How did that work for you?

I got quite a few pieces for free from a wood burning stove store, they are off cuts and second hand pieces.
I went into the shop and asked about buying some, they sold it in 2mm or 4mm I wanted a 250 x 300mm piece it was 60 NZ$ or 90 NZ$ respectively but the guy said they has a bucket of offcuts and replacements in the yard and to help myself.
I also have several  electric cooker tops (ceramic hobs) that I have been given, I am told they can be cut useing a diamond wet saw but I have not tried that yet!
Anyway the glass I have has withstood 547c  but I did crack a piece of second hand and opaque looking 2mm but I have a piece of 4mm over the riser that seems to be perfect for the job.
I have managed to cut my pieces quite easily with a cheap glasse cutter and sanded the edges with a diamond wet stone.

Graham, I don't have fused silica glass here. I looked for glass that tolerates high temperature and stress. Fused silica is pretty much the best you can get. It is used in high-pressure halogen and mercury lamps.

This might not actually be a problem, but I remember the glass in my fireplace insert. It was a high-temperature, high-efficiency (for the mid-90s) unit, and we used it all the time. The cleaning of the glass door had to happen every month at a minimum, or else the flames would be a vague hint of orange behind the soot.

Would soot not accumulate on the glass at the top of the riser, or would the combustion have be so complete as to not be able to deposit soot?

Or is this an issue solved by being able to take the glass top off of the riser to clean?

-CK

I have glass over my fire box and over the heat riser, they stay clear most of the time but like you say ... easy to clean anyway.
I even cook directly on top of the glass, apparently good for 500c but can go upto 700 without cracking, however it does not last forever and repeated heating over 500 will kill it. Or so I am told....
Generally the glass over the feed chamber does not get that hot unless I overload the box and  fire starts creeping up the sticks, the top glass will get foggy at the start but then clears up after a few minutes.

I'm going to try the BBQ and fireplace shops to see if they have any offcuts.  That fused silica glass looks kinda expensive!

i picked up a wood stove door with glass in it so I guess that will be my batch box door now.
I guess I'll have to pass on a riser window for the moment and perhaps get a thermometer to look how well it's burning.

You can drill a small (5mm-10mm) hole in the barrel to look though. (And seal it with clay if not in use.) That is what I am doing anyway, since I can not buy any high temperature glass here.