[Updated below] The problem is, no matter what type of stove I use, or type of cooking setup I try, I get totally lousy burn times for my Esbit solid fuel tabs. So bad in fact, consistently under 7-8 minutes per tab, that I am unable to bring two cups of 70-degree water to a boil in my Snow Peak 600 mug using a whole Esbit fuel tab!
I'm beginning to get frustrated with Esbit tabs. Everyone else seems to be getting burn times of 11-15 minutes from a single fuel tab. John Roan of Mountain Ultralight wrote a fantastic blog post recently about using minimal fuel for trail cooking in which he describes using a single Esbit tab to slow cook a rice-based meal and afterward still having enough of the fuel tab to light it back up and boil water for coffee! What the heck am I doing wrong?
I even made a Gram cracker style minimal stove/holder out of an old Bud Light aluminum beer bottle to see if that would help improve performance, but the burn times were still in the 7-8 minute range.
I'm at the point where the only thing I can think of is that somehow I got a bad box or batch of Esbit tabs from Campmor.com when I ordered them. I bought several boxes at the time (like you do) because I had a coupon, so I probably need to open one of the other packs and test a tab from there to see if they perform persists.
As a fuel option I want to love the Esbit tab. It has all the promise of a robust, lightweight, and hopefully efficient fuel for all types of trail cooking - if I can figure out why mine are not performing anywhere near the range that others are reporting.
What has your experience been with burn times for Esbit tabs? Should I give them another chance and buy some new packs, or just stick with denatured alcohol?
Update with new stove prototype:
Thank you all for your comments and suggestions on how I can try to improve my Esbit burn times. Campmor, where I bought my Esbit tabs from, is looking into whether or not these might be a bad batch, but in the meantime I've been doing a few more burn tests.
I started by using a much more open windscreen to allow more air flow around the burning Esbit tab. I'm using an old windscreen that fit loosely around my Snow Peak 600 and does not suffocate the stove. Just by giving the Esbit tab more air I was able to up my burn times to around 9 minutes!
Next I did a little bit of stove redesign based on some earlier comments I had received via email from Stick of Stick's Blog. He had mentioned that when he recreated the simple Esbit stove that is at the top of this blog post using a PDF template I had sent him, he had bad/slow burn results also. Previoulsy using a different stove he'd had great burn times.
Based on Stick's comments I made a new version of the stove with a few additional folds that created a tray base for the Esbit tab. This allows the liquid that comes out of the fuel tab as it burns to be collected in the ray of the stove and increase the burn time - at least that was Stick's theory!
It's hard to see it in the photo above, but there are tiny little metal flaps that extend from the longer sides and wrap around the edge of the tray, tucking under the folded edge of the side legs to create a pretty decent leak-proof tray.
By adding the tray to the stove so that the liquid from the fuel tab is captured, I increased the basic burn time of the three next tabs to above 16 minutes each. That's more than double the burn rate I was getting.
I'm going to continue to tweak and adjust the stove over the weekend, but this would suggest that the fuel tabs I have are perfectly fine and it is the stove and windscreen configuration that was dramatically reducing the burn times.