Bill Kielb

Thank you Bill as always for your helpful insight. 
We're reaching the end of the firing now, but I am looking forward to pulling the graph from my monitor for the day that shows the TVOC levels. 
PM2.5 levels did not go above 1 both in the kiln room and the house. However, TVOC levels in the kiln room started increasing significantly around the 1800F mark til now (firing to cone 5 - 2150F ish) — they started spiking from 500 ug/m^3 and are now at 2313 ug/m^3 in the kiln room. Indeed it is a helpful reminder of what you said, fumes are not going to be 100% covered by downdraft ventilation and even if like 90% of the fumes are captured, the small % of fumes that are not captured are still pretty bad. Also, I cannot smell anything in the room, but it's a good reminder that smell != fumes as sometimes we can't smell the latter. 
For example, when Skutt says "little to no smells/fumes will leak out of the kiln" — even a small amount of fumes is significant, imo. 
That all said, I've decided that for my own peace of mind I will be relocating the kiln, ideally now to the garage (but this will be determined by if we can get a 240volt outlet routed down there, which will be challenging - contractors coming to quote this week). Another conclusion I've come to from this whole experience is that I also don't think kilns, even small kilns, are suitable to fire in the home. 

Sorry for the confusion, as long as you have enough volume in your house the makeup air from all the little cracks etc… likely is fine as you have run the dryer without issue and it sucks about 200cfm out of the room when operating.. So with the window closed maximum draw will occur from all other rooms which will limit the fumes from exfiltrating to the occupied spaces. If later, running the kiln vent, bath fan, stove vent etc… the volume of your house and normal leaks may not be enough and you will begin pulling from your furnace ….. providing your furnace is a natural draft furnace.
Anyway, two competing issues, pure ventilation and combustion appliance makeup air. Always safe to design in makeup air so combustion appliances behave well. So not a one sized fits all and best done by someone with experience and knows all the components of the home else out of safety you will likely see makeup air always suggested. Like most things if someone is viewing these problems as a stream of airflow, technically this is usually a very flawed view. Folks who do it everyday for real are very cognizant of the pressure difference.
Interesting results from the air monitor btw. I see a lot of general assumptions about vents, kilns and working near them, this may be a nice simple way to show folks All the fumes are likely never captured by down draft ventilation. Your pm 2.5 results seem low since outdoor air is generally above zero. Regardless a nice indicator of trend and your monitor does voc.

A follow up! There's a smell in the kiln room (above + around the kiln), but no smell in the adjacent office room.
Readings:
500F: 
TVOC
Baseline: 0 in all rooms
Living room: 0 
Kiln room: 23 ug/m^3
PM2.5
Baseline: 1 in all rooms
Living room: 1
Kiln room: 1
1200F
TVOC
Living room: 120
Kiln room: 320
We are wondering if we should perhaps close the door to the small kiln room so that the only negative air intake is instead from the leaks around the house. I'm not sure if this would make it spread more or less given that the fan is not venting out all the fumes. (Our stove is electric and furnace intake is from around the house - not near the kiln room). 
I think that given there is still the persistent smell in the kiln room even with the additional fan venting out -- I am considering to move the kiln to be right in the corner between the two windows (health is first..). 

I think I would like it in the tool tip but not knowing what data are available may not be the best choice so I will review the Genesis tonight. This is a cool project, just wondering if a universal excel template might suffice. No matter - nice project.

A lemon test won’t rule anything in as safe, but it will rule out things that are susceptible to acid. That said, alumina isn’t a super volatile material in ceramics, and generally* adds to the durability of a glaze. It’s pretty refractory. That said, if it’s a dry, powdery lump of kiln wash sticking out of the glaze, that’s not good for craftsmanship or aesthetic concerns. You could try glazing over it and re-firing. 
Even if the alumina was not bonded and someone ate out of this piece, you also have to consider whether there’s enough material there to do damage to anyone. I’m not saying you should leave kiln wash bits embedded in your piece. I say that only to contextualize potential risks.
*assuming the rest of your materials are also within reasonable parameters, and the glaze isn’t already an alumina matte, which would be a logical assumption in a liner glaze. 

OK, I will cross my fingers and be very careful.

Might help, my experience as an old guy  - oil burners are pretty old technology so lots of reading if you just  Google oil burners. Some  decent plain English reading here IMO  https://inspectapedia.com/heat/Oil-Burner-Nozzle-Selection-Guide.php#FiringRate. Picking a correct pressure important, used to be no less than 100 psi which has grown to 140 psi for finer droplet size, better aeration. 140000 btu per gallon is how I learned it (no2) and nozzle dispersion critical to cover the firebox without impingement. Anyway, pressure, size, cone angle all contribute significantly and mostly really good filtration to avoid clogged nozzles.

Might help, my experience as an old guy  - oil burners are pretty old technology so lots of reading if you just  Google oil burners. Some  decent plain English reading here IMO  https://inspectapedia.com/heat/Oil-Burner-Nozzle-Selection-Guide.php#FiringRate. Picking a correct pressure important, used to be no less than 100 psi which has grown to 140 psi for finer droplet size, better aeration. 140000 btu per gallon is how I learned it (no2) and nozzle dispersion critical to cover the firebox without impingement. Anyway, pressure, size, cone angle all contribute significantly and mostly really good filtration to avoid clogged nozzles.

Pictures definitely key here as I have seen circular failures and delaminating especially in bowls where the interiors were overworked in the green stage. Pictures and a little about any special throwing, trimming, ribbing, burnishing etc….  could help narrow this down.

If no need to be double sided - conventional masking tape? There are a variety of adhesives, fine line, etc, to choose from and they are available in different widths.

If no need to be double sided - conventional masking tape? There are a variety of adhesives, fine line, etc, to choose from and they are available in different widths.

Hey Bill, Thanks for your advice! So I did a quick segment programming like you suggested. I couldn't empty my kiln at the moment, so I only ran it for about a minute so I wouldn't compromise the pieces. But I heard a lot of buzzing and it got hot in inside quick. I didn't see any glowing coils, but I think its because I only had it running for a short minute. 
I'm feeling better about it all, now i'll just wait for a day when its not raining outside. 
Thank you again!
 

Just a quick mention
Neil makes a good point and without looking closer 8” combined is likely fine. Just a caution, while not the best it would be most correct to install backdraft dampers when combining exhausts so when one fan is not in operation the other will not have a short circuit path.
 
Actually just best to run them out independently as designed. 200 cfm in 6” round is over 1000 fpm which is significant. This is not worth calculating really and to do so is a bit complicated and requires actual airflows. Separate discharges most goof proof solution.
 

You might be interested in AC infinity. I have had them installed in several kiln rooms and model dependent they come with a temperature controller which varies the speed as required. Very quiet fans for the most part at what I think are reasonable cost. Google Ac Infinity.

No, you don't want this additional vent on the same duct line as the vent, as it will affect the draw of the kiln vent. The fan I linked to needs a 6" duct and the Envirovent needs a 4" duct, so if you wanted only one hole in the wall you could do a single 8" hole and use a Y duct that splits into a 6" and 4". Another option would be the 4" version of the vent, which would allow for a single 6" hole that splits into two 4" ducts. The 4" version has 1/2 the power of the 6" though.
The one I have in my shop is fairly quiet, but I don't know the actual db output. If you had a couple feet of flex duct between the motor and the hole that may help to dampen the noise.
Not plug the lid hole, but cover one of the holes in the cup under the kiln.  

Not sure   but blue for me,  I have to mix a little frit into the  blue underglaze so it stays smooth under the glaze. A little of the glaze if it is a non run clear would also sort this. As it is not all over your blue dec.  Could it be the rough patches are applied thicker when brush fully loaded? Or underglaze not stirred between brush strokes? 

Roughage!

The counter flow vents can vent some of the fumes, even let’s say many fumes but they will not get them all. It cannot have enough power or airflow to offset the buoyancy of warm air. If it did, your kiln would not have enough power to make temperature because of all the air necessary being exhausted from the kiln would be a giant heating load.  Sort of like firing with the lid wide open. So here counterflow vents are a reasonable compromise solution.  Wax that burns off in the temperature range you describe is particularly noticeable but other fumes obviously are emitted, even those that most cannot smell. If we put a Pm2.5 particle detector (popular these days) in the vicinity you likely would see an immediate rise in particles detected when running your kiln. I mention this because the new IAQ indoor standards have made these air monitors accessible and relatively affordable these days. It does allow potters (with better accuracy than the smell test)  an easy way to verify with greater confidence their system appears to be performing as expected.
 
Without getting into a giant discussion of best practice, exhausting the kiln room and keeping it slightly negative (lower pressure) with respect to all adjoining spaces is a proven technique. From bathrooms to clean rooms, even surgical suites. This means an exhaust fan where some of the makeup air MUST come from the other spaces is important. We only want air leaking into the kiln room from other spaces. If you open a window in the kiln room and it supplies ALL the air to the exhaust  the kiln room will not be negative (lower pressure) with respect to the other rooms and exfiltration (or kiln odors leaking into other spaces) may still prove troublesome. These are fairly simple designs for folks that have done it; however well meaning or not, I have seen lots of well intentioned but less than ideal advice on this.
My thought is best to describe how it ought to work and you will be able to keep that fundamental in mind as folks suggest things. It needs to work just like a bathroom fan, only air is allowed to leak in from the other spaces. Simple really.
Your kiln vent could exhaust some of this air, but realistically the amount of actual exhaust is on the order of 10 cubic feet per minute. New bath fans will be 50 - 100 cubic feet per minute for some perspective. If you have a dryer that exhausts (non heat pump) then that machine will exhaust approximately 200 cubic feet per minute. You could test your next firing with it running to see if that will be sufficient exhaust to keep the room exhausted. If so, the addition of that sized fan might be a simple solution.

I have measured these in operation, with all the small diameters and restrictions they do not flow more than 20 cfm. It’s rated 140 cfm in free air. Configured as downdraft it does not exhaust nearly that much. Old video here but measured from two kilns was less than 20cfm. https://youtu.be/etpa2Pc9Hug?feature=shared
 

The fans blowing in have a chance of pressurizing everything so I am trying to get you to an exhaust solution which we know will work. The kiln vent is such a small exhaust. I would feel better with a bath fan in the kiln room and the office window opened slightly as an easy test.

The counter flow vents can vent some of the fumes, even let’s say many fumes but they will not get them all. It cannot have enough power or airflow to offset the buoyancy of warm air. If it did, your kiln would not have enough power to make temperature because of all the air necessary being exhausted from the kiln would be a giant heating load.  Sort of like firing with the lid wide open. So here counterflow vents are a reasonable compromise solution.  Wax that burns off in the temperature range you describe is particularly noticeable but other fumes obviously are emitted, even those that most cannot smell. If we put a Pm2.5 particle detector (popular these days) in the vicinity you likely would see an immediate rise in particles detected when running your kiln. I mention this because the new IAQ indoor standards have made these air monitors accessible and relatively affordable these days. It does allow potters (with better accuracy than the smell test)  an easy way to verify with greater confidence their system appears to be performing as expected.
 
Without getting into a giant discussion of best practice, exhausting the kiln room and keeping it slightly negative (lower pressure) with respect to all adjoining spaces is a proven technique. From bathrooms to clean rooms, even surgical suites. This means an exhaust fan where some of the makeup air MUST come from the other spaces is important. We only want air leaking into the kiln room from other spaces. If you open a window in the kiln room and it supplies ALL the air to the exhaust  the kiln room will not be negative (lower pressure) with respect to the other rooms and exfiltration (or kiln odors leaking into other spaces) may still prove troublesome. These are fairly simple designs for folks that have done it; however well meaning or not, I have seen lots of well intentioned but less than ideal advice on this.
My thought is best to describe how it ought to work and you will be able to keep that fundamental in mind as folks suggest things. It needs to work just like a bathroom fan, only air is allowed to leak in from the other spaces. Simple really.
Your kiln vent could exhaust some of this air, but realistically the amount of actual exhaust is on the order of 10 cubic feet per minute. New bath fans will be 50 - 100 cubic feet per minute for some perspective. If you have a dryer that exhausts (non heat pump) then that machine will exhaust approximately 200 cubic feet per minute. You could test your next firing with it running to see if that will be sufficient exhaust to keep the room exhausted. If so, the addition of that sized fan might be a simple solution.

No worse that any other forced air system. Follow basic cleaning guidelines (wet cleaning- mop, sponge, etc) and you shouldn't have anything to worry about.

martinja, do you have only a few members or are there people tracking floor dust all over all day?   keeping good cleaning working habits are the safest way to avoid dust.   add some containers to all areas and tables so small bits can be tossed into them instead of being brushed onto the floor by sleeves or other items.  put up signs and teach any new person exactly what you expect from users.   clay is easer to clean if it isn't there.

Could be the glaze layer at the rim is thinner.
Could be the rims were worked more at finishing, hence sand and/or grog are more exposed.
Could be a combination of both?
Reglazing and refiring, hard to say; some have luck with that, some don't.
Any road, building up a slightly thicker layer of glaze at the rim might help.
Using glaze that doesn't move/sag much might also help.
I'm curious if the problem mugs are together in the kiln, perhaps a hotter area?
I've used a buff stoneware that weeps tiny droplets when fired hot. The droplets stick but can be scraped off bare clay (e.g. the foot ring). The droplets will be hidden in the glaze layer, where the glaze is thick enough, else there's a gritty feel.
It's annoying! ...haven't seen it in any other clay, just the one buff stoneware.

Mug rims need to be rounded, and you should never sponge the rim or it will get rough (if you're using stoneware). The sponge removes the fine particles in the clay and exposes the larger particles. If you do have to sponge it, go back over it with your finger and a tiny bit of water. Also make sure the lip has a good glaze layer. A thin rim is more comfortable to drink from, but too thin and it won't take glaze well, especially if you're dipping, because it can't take in enough water to leave a good deposit of glaze.Too thin a glaze layer and it'll feel rough.