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Old 11-01-2009, 07:48 PM   #126
Ran D. St. Clair
Senior Member
 
Join Date: Apr 2009
Posts: 212
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One More Toilet Mod

I hesitate to mention this, because I am not sure if it was worth the effort, but I wasn’t happy with the idea of digging out a bunch of mineral wool every time I needed to vacuum the ash out the burn chamber. The mineral wool itself is fluffy, like heavy cotton balls, and I am pretty sure it will gradually get lost, and dirty, and blown away by the wind, as I pull it out and put it back in time after time. I was also worried that it was itchy and slightly bad for you, like fiberglass insulation, though I must admit, after working with it a bit, it doesn’t seem to be.

My idea was to define the opening to the fire box plug with a layer of high temperature silicone, and then further create an insulated plug of mineral wool and high temperature silicone. The idea ultimately worked, but it was not easy to do.

I began by opening the fire box access doors, and removing mineral wool to access the plug. I then removed the plug and taped over the opening with scotch tape to protect the internal threads. I then shaped the mineral wool around the opening to allow access to the plug including room for my fingers to grab onto the plug.

The original plan was to just smear a layer of silicone onto the surface of the mineral wool. That plan lasted about 30 seconds as I quickly had silicone all over my hands with nothing stuck to the mineral wool. I then found that I could force the silicone onto the surface of the mineral wool with the caulking gun by laying down successive beads, much like piping frosting onto a cake. This only worked for surfaces from horizontal to near vertical as the mineral wool wasn’t strong enough to hold the silicone against the pull of gravity. I then tried laying pieces of fiberglass cloth into the wet silicone, which worked fine as long as I only touched the dry side of the cloth. I then found I could apply the silicone to the cloth and then press the cloth into place against the mineral wool. The trick is to not get too fussy and try to work it too much. As soon as you get silicone on to your fingers or whatever tools you are using they get sticky and it is time to stop.

After the silicone was cured I was able to go back over the surface of the cloth with a layer of smeared silicone. At this point I could also make a good seal around the access pipe and to some degree around the opening to the sliding metal door in the outer fire box. The trick here was to avoid jamming the door slide with silicon. Fortunately the silicone remains fairly soft after it is cured and can be scrapped away if necessary. When everything was cured I removed the protective tape and installed the metal screw plug.

The making of the silicone plug required a different technique. I started with a large ziploc bag with the top Ziploc portion removed. I then filled it with the mineral wool that I had removed from the fire box, wrapped it up tight and pushed it into the opening on top of the screw plug. I mashed it into place and closed the sliding door behind it just to make sure it would fit. I then gently took the bag out again which allowed the mineral wool to hold the rough shape of the plug.

This next bit is tricky. I opened the bag but left the mineral wool plug deeply seated in the bag. I then piped heavy beads of silicon on top of the mineral wool while it was still in the bag. I couldn’t get to all sides of the mineral wool but I was able to cover about 2/3ds of it. Then I wrapped up the bag tight and shoved it back into the opening behind the sliding metal outer fire box door.

Normally the silicone would set up in 24 hours, but the bag was preventing a free flow of air so it was setting up more slowly. After 24 hours I was able to open the sliding door and open the back of the bag just enough to let some air in. The silicone in that area was partly set at least enough to hold its shape roughly, and even if it had distorted a bit it wouldn’t matter because the whole thing is spongy and meant to conform to whatever space it is forced into. After a few more days the silicone was set all around and I could remove the partly formed plug.

I then opened the bag and added a heavy layer of silicone to the exposed mineral wool areas just like before, then wrapped up the bag and stuck it back into the opening to cure. When it was partly cured I opened the back of the bag just like before. After it was fully cured I removed it from the bag and I had my fully formed plug, but it was all wrinkly and ugly from the folds in the bag. I could now trim off any unwanted silicone with scissors and then smear on a final layer of silicone to smooth things out and make it look nice. Finally I baked it for a couple of hours in a 350 degree oven just to make sure the silicone was fully cured.

The end result is a custom fitted silicone bag full of mineral wool. Will it hold up to many years of use? Ask me several years from now…. I have installed it and removed it several times now, and so far so good. A picture is available under keyword “Stealth”.

To be continued….
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