New Improved Malt Kiln for Diastatic Brown Malt

So you want to dry your malt with a wood fire (because it’s awesome) but you live in a townhouse, what to do?

I recently received some questions about diastatic brown malt from Ryan Pfeifle at Farm Power Malt in Montana who is experimenting with making it on a larger scale. His interest inspired me to give it another go. It’s been a while since my last experiments and I’ve learned a lot since then. I also figured it was about time I fix this darn barrel kiln sitting in my garage. My next post will be about brown malt and the beer I’ve made with it, this one will just focus on the kiln which is working really well. The “air on” temperature sits solidly at 225F with one large gassifier. I’ll be tweeking this perhaps with some venting to make it more adjustable. The malt temperature did not go higher than 206F which is great, it’s where I want it, hot enough for colour but low enough to preserve the enzymes.

So this is more like how I imagined it in the first place. The top of the original barrel acts as the heat disperser and the new half barrel sits perfectly inside the outer rim. I placed 4 bolts 9 inches up from the bottom of the half barrel to hold the Webber grill which is a good width to fit in a barrel. You can buy these at the Home Depot, they’re a little pricey for what it is at $30 but since I didn’t have any other ideas for the “grain basket” I had to buy it. I placed the thermometer just under the grain bed to measure my “air-on” temperature and I’ll use my probe thermometer for the malt temp.

The insulation was also a little pricey, there are probably other options for insulation. The stuff I bought is called Fiberfax which I bought at Greenbarn. For the inch thick blanket it’s about $8.50 a linear foot (comes in 2′ wide rolls) For the 1/2 inch it’s about $5 per foot. It’s rated to 2400F so it’s definitely good enough for this application. I bought 6 ft. of the 1″ thickness but I would have been fine with the 1/2 inch stuff. Beware though that this stuff is seriously toxic, you can see the fine silica particles in the air when you handle it. I wore a respirator and goggles when I worked with it. I originally glued the insulation to the inside of the barrel with something called sodium silicate which worked but I wanted to protect the insulation and I wanted to protect my malt from any particulate matter that the insulation might impart so I bought some steel sheet metal thin enough to bend into a circle to cover it. The sheet metal is just sitting on three 2″ bolts.

Once I make or find a proper basket for the grain I’ll be really happy with this kiln. There are times in my life when I feel like Richard Dreyfuss in Close Encounters with the Third Kind, the part where’s he’s obsessed with constructing Devil’s Tower in his living room.  “Well I guess you’ve noticed something a little strange with Dad” That’s when I know I’m doing something worthwhile, at least that’s what I tell myself.

 

 

New Malt Kiln

This project was way overdue, maybe a few years overdue, but I finally built something to kiln in besides my oven. As I stated in the video using the oven just became too inconvenient. My wife also makes custom order cakes and she’s been getting more orders lately so I had to free up the oven.

So far I’ve only done one small batch of Brumalt in it and I was impressed by how well it worked. The temperature stayed consistent and with only two vent holes open the heat stayed in and there was plenty of airflow. I didn’t even turn the fan on and I think I might only have to when I’m doing larger batches over 5 lbs. This small 2.5lb batch of  brumalt dried within 6 hours which is quite fast and it was so nice to have it stew for 18 hours without having to worry about someone turning the oven on accidentally (which has happened).

One thing I might add is something to disperse the heat when I’m using screens. The hot plate sits in the center of the kiln and it seems that the heat is more concentrated in the center although I haven’t measured this yet. I’m not concerned when the perforated steel tray is in there because these holes give an open area of 40% so the tray itself seems to disperse the heat well enough. I may just add a spare piece of the tray material under the screen to disperse the heat.

I don’t have any carpentry experience so I’m sure there are better ways to build a box but here are the dimensions that I used.  The front and back are 24″ by 24″  The sides are 20″ by 24″  Because I’m using 3/4 ” plywood the top and bottom dimensions are 20″ by 25 1/2″.  It’s held together with 1 1/2 ” drywall screws with a little bit of wood glue. The 6 vent holes are 1 1/2 ” which I used a hole cutter bit on my drill to cut out. I pre-drilled some holes for the vent covers and then on the on the covers themselves I drilled holes wide enough to accommodate the 1 1/4″ screws so the covers could move without releasing the screw from the main lid. I had the cutting done at the Home Depot because it takes them a few seconds to get a perfectly straight cut. The piano hinge is also from the Home Depot. For the fan hole I used a jigsaw to cut a round hole and it’s not pretty, luckily it’s covered up by the fan. 

 

 

New malt kiln

Still on the quest for a more authentic diastatic brown malt. I was pretty disappointed with the soot that appeared on my last batch and I wanted to play around with using higher temperatures so a new kiln was in order. Unfortunately I live in a townhouse, otherwise I would have built one by now using cinder blocks or anything I could get my hands on. Instead I had to settle for something on a more portable scale. I had originally thought of using a barrel so that I could take it to a campsite close by and put it over a fire pit, that way I could try using straw as a fuel. Then I figured why not use the gassifiers in the barrel, it’s clean, very safe, and I get one hour of burn time for each load of pellets. Every time I try burning straw it burns faster than paper, I still don’t get how this was used in the early malt kilns.

As I mention in the video I just didn’t have the time to perfect the design and my malt was at 10% moisture level after air drying for two days, it was more than ready to be kilned. The temperature crept up to 250 by the end of the first hour, there was still steam coming off at this point. During the second hour the temperature rose to 275 and then to 300 during the third. I knew this would probably be too hot for the malt to have any diastatic power left to convert itself but I wanted to see how a faster and hotter kilning would affect the colour.  My results were most likely inaccurate because even though my oven thermometer read these temperatures the heat coming out of the small holes in the barrel was much higher. The 4 oz. test batch came up with a 1.020 original gravity after an 8 hour mash.

Well at least now I know I can make a pretty descent blown malt, check out the snapping action in the video. As well this would be a great way to roast your grain outside, you could easily do 7 pounds at a time this way.