- Oct 16, 2015 at 7:59 pm #2232463
> In a conversation with a T.D. designer he mentioned that the Gram Cracker's advantage was controlling the burn by containing the sides of the tablet. As an observational note of the pop-can burner, when burning it looks like the flame is floating. It appears, to me, that what's burning are fumes and not the actual tablet. I would guess—and this would need to be tested—that lipped trays are more efficient because the contain the flammable gas. If this is true then the followup question would be what is the most efficient volume and wall height to base ratio. With regard to burners vs. system testing I think system comparison are good because they establish a benchmark of total efficiency. For example, I know from reading many threads on alky/esbit stoves that it is reasonable to expect just over 6 minutes to boil two cups of cold water with a single large ESBIT tablet or half ounce of alcohol. Edit: clarity.Oct 16, 2015 at 9:07 pm #2232474
Richard, First I want to thank you for starting this thread. It inspired me to do a lot of testing for myself, and I learned a lot along the way and I'm pretty sure others have as well. Heck, it even turned me into an Esbit fan, and I never expected that to happen! Regards to burner design, height etc, I did a whole bunch of testing (some of which was previously detailed in this thread and elsewhere) and finally settled upon a "legless BGET" and my own pot support which I believe added to the efficiency of the system. Recently I also replaced my aluminum windscreen with a titanium windscreen (rolled up for storage) because the aluminum one developed splits where it was folded after many uses and had to be replaced. The Ti screen should, theoretically, last forever. I also never expected to end up with an aluminum pot, but now the Open Country 3-cup hard-anodized Aluminum has become my favorite. This is where logic and testing have led me. With my setup I have never failed to achieve a boil of 3 cups of water (starting temp down to 48degF IIRC off the top of my head) with one 14g tablet. This is important to me because when out backpacking I have settled upon a routine of 3 cups in the morning — 2 cups coffee, 1 cup for oatmeal — and 3 cups in the evening — 1 cup coffee and 2 cups for dinner. IMHO, the time to boil is, within reason, a non-issue compared to fuel efficiency. For instance, what difference does it make if I can boil my needed 3 cups in 11 minutes and continue to boil for 2-3 minutes (which is the norm for my setup), or to boil 2 cups in 6 minutes and not have enough hot water for dinner or breakfast? For my needs, I'll take a few extra minutes to get the greater amount of water boiled with the same amount of fuel.Oct 16, 2015 at 9:27 pm #2232479
> … what difference does it make if I can boil my needed 3 cups in 11 minutes and continue to boil for 2-3 minutes (which is the norm for my setup), Now, you see, that's where things get interesting. I hadn't tested for 3 cups, and that target makes a lot of sense for your needs (and I like it for similar reasons). My next day off I think I will do a test. It probably won't be as efficient since I use an 850ml pot with a narrower base. But, if I get a boil with a single tablet then it doesn't really matter. Hopefully the loss of efficiency will be absorbed by the extra 2-3 minutes you get on your kit. I think efficiency should be defined as fulfilling one's needs rather than by the stricture of metrics. "Three cups with one tablet per meal" being an excellent example.Oct 17, 2015 at 6:00 am #2232505
This all reminds me, I've got quite a collection of barely used test pots to sell on Gear Swap. :^)Oct 20, 2015 at 11:36 am #2233004
So, poking around my local store I found the SOL All-Weather Fire Cubes. Here's what happened when I burned one. Essentially it starts with a simple spark, burns for about 12 minutes, produces a very strong flame at the beginning and leaves a lot of soot on my pot. The tablets could boil 2-3 cups of cold water depending on the cook kit. Because of the smoke I think I will only use this to fire up my grill or fire. It is supposed to be waterproof so a tab or two may come with me in my emergency fire kit. I don't know what the fuel actually is, though I'm sure it's a variation on ESBIT. The complete set of high-res images are in my Flickr starting here: https://www.flickr.com/photos/richardmaycr/22300618722/in/album-72157651260318840/ After a mere 18 seconds the flame was really high and seems to have reached it's peak because it slowly died down after this. . By 9:07 the flame died down substantially and somewhat abruptly. . It was out a few seconds after 12:42. . It left a pile of ash and a button of unused material. I couldn't get the button to start so I wonder if it actually had any fuel left. . Contrary to manufacturers claims it produced a heavy black smoke that leaves a thick layer of soot on the pot: . . For comparison this is what an ESBIT tab leaves behind: .Oct 21, 2015 at 1:32 am #2233125Adam KilpatrickBPL Member
@oystersLocale: South Australia
Oh man, think I'll avoid those SOL cubes, the mess left looks disgusting. Thanks for posting that Richard :-) In other news I ordered the new Gossamer Gear esbit/caldera cone/fosters pot kit. Will take some weeks to get to me in Australia. Once I have it I'll do some tests to add to here, including a couple of videos of it with a thermal camera. I'll do thermal video with a pot support (sans windscreen) that Zelph sent me too. Then I think I also need to cut down on gear that I have lying around for simplicity sake. The Gossamer gear kit (plus a spare pot or two) for solo trips, and probably my Firelite 1350 SUL Ti pot with MSR Microrocket, Ti Caldera and alcohol burner for other uses (group trips, international trips). Decision paralysis otherwise.Oct 21, 2015 at 5:12 am #2233133
Ick! Thanks for saving me some time even testing it. Looks perfect, however, for starting a fire under truly dire circumstances with wet wood… when you're otherwise well and truly SOL (S#!t Outta Luck).Feb 14, 2016 at 1:33 pm #3382020
Just thought I would add some data to this thread, I did not realize it existed and started another thread regarding esbit testing.
I finished a home made cone for a grease pot today. I wanted to get some data on how fast it would boil 2 cups of water. My previous experience was with a primus eta power pot with a heat exchanger. I did not write things down, but my memory tells me that with this cone and a different stove setup (not the Epicurean made by Flatcat Gear) it was around 8 minutes for 2 cups.
Today I ran two tests. Did this outside at 60F, no wind and basically sea level. The first was 2 cups of water to rolling boil in 6:30, at least that was when I heard it and lifted the top. That used 10 of 12g of 2 round Couglans fuel, epicurean stove by Flatcat gear and home made cone with a grease pot. The lid is the grease pot strainer with foil covering the holes. Decided to try again and this time measured the starting water temperature at 59.4 F. I started 2 fresh Couglans tabs and did a few things. When I returned, I could see the flames licking around the bottom of the pot through the holes in my cone. I decided to peak at 5:18 to discover that I had already achieved a rolling boil, but was not seeing the steam due to either darkness or who knows. This time I had 4g of fuel left over. Earlier I did try boiling 2 cups on 1 Couglans tab to no avail.
But, the first tab was laid flat side down. When I burned 2 tabs, I had them round side down and side by side to fit better in the Epicurean. I am starting to wonder if I do 1 tab on the round side if I might just get the two cups to boil.
Reading a bit of the first page I see that getting 4 cups to boil on 14g of esbit fuel was very close to being achieved, so it seems that possibly getting 2 cups to boil on a 6g Coughlan’s tab is within reach. I will have to give that a go.
MattFeb 14, 2016 at 4:07 pm #3382059
So I gave the one 6g Coughlan’s Esbit tab and 2 cups of water a go. I used by digital reptile cage thermometer to measure temperature rise versus time and was recording data every 15 seconds. Water temp at test start was 65F. Around 4;40, my thermometer decided it had maxed out. I am guessing 160F is its max, as the last reading I got was 155. I kept watching and listening, as I projected at 6 minutes I would be at 195F if the temp kept going up at the same rate. Just before 6 minutes I heard simmering sounds,. That lasted for about 30 seconds, and then quieted. I guessed the fuel had run out, and lifting the pot I saw my assessment confirmed. Outside conditions are 79F and calm (yes, I live in SoCal, please send your rain this way . . . ).
So it does not appear that 6g will boil 2 cups of 65F water here at sea level, but all in all I am pretty happy with this setup.
Kmart grease pot with strainer lid and al foil, Flatcat Gear Epicurean Titanium UL 15, home made al flashing cone for wind shield and pot support. Not super light, but it is my first attempt at a ULish setup and it meets my budget and versitilty desires. Numbers in table below are grams, you can see the windscreen is a bit of a hog as is the pot, but for two people not so bad.
Edit – tried to copy and paste weights from my drive spreadsheet but formatting got lost.
Kmart grease pot 69g, strainer lid with al foil 22g, epicurean stove 9g, ground reflector 6g, homemade cone 45g, total 151g or 6.4 oz.
MattFeb 14, 2016 at 10:06 pm #3382135
One thing I have been wondering is why I read very little to nothing about people burning Coughlan’s tabs as opposed to the “original” Esbit? I will admit that in some stove setups the Coughlan’s seems to burn a bit dirtier and not get fully consumed. In the Epicurean I have not seen that to be the case. And the price is 2:1 cheaper, even considering the tabs are smaller. I bought a lot of 144 tabs on ebay for just under $20 last summer. That is <30 cents for 2 6g tabs, which are pretty darn close to one esbit tab. Looks like they are going for closer to $30 for 144 tabs now, but that is still a significantly less. Also, seems a bit easier than cutting cubes in half.
edit – I did just find a vendor called leftlane sports that is selling esbit 14g cubes for $4.95 with tax in CA at least and 5.95 shipping. If you buy 5 or 6 the price is just over $6 each which is not too bad. buy $75 worth and get free shipping.Feb 15, 2016 at 8:36 am #3382162
Bob Moulder said:
Regards to burner design, height etc, I did a whole bunch of testing (some of which was previously detailed in this thread and elsewhere) and finally settled upon a “legless BGET”
I agree with Bob, those have been my findings also.Feb 15, 2016 at 8:40 am #3382164
Adam, summer is almost over for you, looking forward to your thermal testing of the new gossamer Gear kit :-)
In other news I ordered the new Gossamer Gear esbit/caldera cone/fosters pot kit. Will take some weeks to get to me in Australia. Once I have it I’ll do some tests to add to here, including a couple of videos of it with a thermal camera. I’ll do thermal video with a pot support (sans windscreen) that Zelph sent me too.Feb 15, 2016 at 10:34 am #3382188
Matt, I will chime in here with some impressions of the Coghlan’s round fuel tabs. First, I repackaged a bunch of tabs, 5 to each vacuum sealed bag for use in screw-top bottles designed to hold a roll of quarters. As a true OCD geek would do, I weighed each tablet to a tenth of a gram. The average weight was 6.8 grams/tab, and I separated them into groups according to weight (6.7. 6.8, 6.9, and 7.0 grams; those less than 6.7 grams went into the “firestarter” pile).
I dearly wanted to achieve a 2-cup boil with one tab, using water of a starting temperature of 45* F (from my refrigerator, which is also about as cold as our mountain water might ever be during the summer). I couldn’t get a boil, ever. Then I wondered if I could get a boil with just 1.5 C. of water (for coffee). I almost did, or at least it would work for treated water for a cup of Via. 1 cup was easily achieved with a single tab. So I think I can get by with using 2 separate tabs for my 2 cuppas. Dinner, with its 2 cup requirement, would certainly require 2 full tabs being burned at the same time. Keep in mind that my tests were done with a MYOG caldera “clone” on my patio, which is at 5440 feet elevation. The ambient temperatures ranged between 45-55* F, with minimal breezes.
I learned a few things through my testing. First, the Coghlan’s tabs don’t seem to burn all the way down to ashes like Esbit does. There was always a small bit of unburned fuel at the bottom center of the tabs, apparently smothered by the overlying ash. Secondly, there seemed to be about the same amount of residue deposited on the pot bottom as Esbit does. Thirdly, I had a sneaking suspicion that the distance from the top of the Coghlan’s tab to the pot bottom needed to be different than the 1.25″ I have settled on with Esbit and Bleuet and Firelite tablets. After several tests, I came up with an “optimal” (?) distance of about 1.0″, or perhaps even .875″. I seemed to get some oily residue on the pots from the shorter distance, but I also got the water to get hotter faster. Hmmm…closer to the hot flame, but some incomplete combustion?
Here’s a photo of my Esbit holders side by side with those for the Coghlan’s tabs. Hopefully you can see the height differences of the top of the tabs–1.25″ to the pot for Esbit, and 1.0″ for the Coghlan’s. I made a BGET with side extensions for the Esbit (well, a Bleuet tab in this photo, but its dimensions are identical to an Esbit), and I’m rather proud of my creation to hold 2 Coghlan’s side by side vertically (again with removable extensions).
Here’s a close-up of the Coghlan’s holder. The side and end extensions are removable to more fully expose the tabs for a more robust (and faster) burn. I placed a small piece of carbon felt under the elevated burner to help insulate it from the cold sink from the ground. There is a small rectangular base that the felt and stove “legs” fit into which holds everything together (barely). Then there’s the obligatory circular titanium base disk. It’s likely something that only a mother could love, but at least I think it’s cute, and pretty functional.
The bottom line on these solid fuel tablets, for me, is that nothing works as well as Esbit. The orange Bleuet tabs have performed a bit less than Esbit–close, but not quite as good. The Firelites that I bought years ago at BPL’s Gear Shop are OK, but the paraffin tended to escape in some of my burners (that’s when I became a fan of the pop can holder). For me, the main positive quality of Coghlan’s tabs is the price, as I’m seeing a somewhat lower quality with them (I think, so far). By the way, I did contact Coghlan’s about their tablets. I asked them if there is a way to do a 2-cup boil with one tablet. The response was this: “It would indeed be difficult to get a 2-cup boil with just one tablet. We recommend using 2 or 3 to achieve that.” Hmmm…Esbit for the win!
By the way, what is this liquid thing everyone’s concerned about? I see zero liquid when using Esbit, Bleuet, or Coghlan’s. Only the Firelite’s added paraffin needs some containment.Feb 15, 2016 at 1:38 pm #3382222
Wow Gary, what a great detailed response. I will comment on a few things above. Not meant as a rebuttal in any way, just my observations I likely did not articulate above or from past experience.
The average weight was 6.8 grams/tab My scale weighed my tabs at 6g, but likely it is just a cheap scale. The resolution is only 1g, so I am sure it is measuring a bit low.
Dinner, with its 2 cup requirement, would certainly require 2 full tabs being burned at the same time. I did achieve a 2 cup boil with 2 tabs with 4g of fuel left over, albeit with water starting at 59F, not 45F. I would like to re-run this test at 45F. My boil temp is a bit higher since I am as sea level.
I learned a few things through my testing. First, the Coghlan’s tabs don’t seem to burn all the way down to ashes like Esbit does. There was always a small bit of unburned fuel at the bottom center of the tabs, apparently smothered by the overlying ash. I had the same experience as you until I started burning the tabs on end, oriented as in your BGET with the Coughlan’s tabs. The amount of unburned fuel is nearly zero, and the ash is much less as well. The only stove I am using presently is the Epicurean, so YMMV in different stove setups.
I made a BGET with side extensions for the Esbit, and I’m rather proud of my creation to hold 2 Coghlan’s side by side vertically (again with removable extensions). Nice! When I tried making my own burners they were much more, um, prototype than yours. Actually prototype is a bit of a stretch even . . .
By the way, what is this liquid thing everyone’s concerned about? I notice the liquid more when I use the Epicurean in simmer mode. The material liquefies when it burns, and the unburnt material can end up in a puddle at the bottom of the burner. I have not tried “simmering” with the Coughlan’s on end yet, so I am not sure if I will still see it then. I do know with my other stove creations, even using Esbit, I have observed the “liquid”. Mind you by the time you see and touch it it is a solid, but it is fairly easy to tell it “flowed” from the solid fuel.
Out of this I see two tests I would like to run. one is the two tabs of Coughlan’s on two cups of refrigerated water. The second test I would like to run is a single esbit and 4cups water vs 2 Couglan’s and 4 cups water. I don’t expect to see either one make the water boil. I would like to measure the temperature rise versus time see the comparison of temperature rise and burn time in my Epicurean stove.Feb 15, 2016 at 2:03 pm #3382227JeremyBPL Member
I may have missed it reading through all 9 pages, what’s the height of the TD Gram Cracker with a 14g ESBIT?Feb 15, 2016 at 4:33 pm #3382250
Jeremy, in my TD Gram Cracker holder the top of a 14 gram Esbit tab sits 1-5/16″ above the table top when used in the usual mode. If I turn the holder upside down, then the tab’s top is 1-3/16″ above the table top.Feb 15, 2016 at 5:00 pm #3382254JeremyBPL Member
Thanks!Feb 15, 2016 at 7:48 pm #3382276
Test 1 done. 2 Coughlan’s tabs heating 2 cups of cold water. Water was 35F at start. Epicurean stove, home made cone, 4.5 cup grease pot with al foil on top to cover holes. Temp was 149 at 4.5 minutes, and the thermometer went over range before 5 minutes. So over 120 degrees in 5 minutes, with about 50 more degrees to go, so about 2.5 minutes to 212F likely. At 6.5 minutes I heard simmer sounds. At 7.5 minutes I called it “rolling”. This is in line with the approximate temperature rise I had measured and calculated in my head above. Did not see any reason to try to be super precise as let’s face it, this sort of data has lots of opportunity for small (and big) errors.
I had the cover off a lot between 7 and 8.5 minutes. At 9 minutes I called it “Super roll”, which I suspect is really 212F here at sea level. Wish I had a good indicator for this time period, as if the temp kept going up linearly I would have been way over 212 by then. But I do know phase change is a great thermal conductor. Boiling kept at this level until 10:45, when it quieted a bit. At 11 minutes it was a simmer, and at 11:30 it was out.
I will update this later with a couple of pictures of the tablets before and after burn.
One pic shows both new tabs and what was left of the burned ones. There is also a bit of unburned liquid on the tray. My picture of the ash did not come out well, may just pass on that one.Feb 15, 2016 at 8:33 pm #3382281
Second test, 2 Coughlan’s tabs and 4 cups of cold water. Start temp was 42F. No boil as expected. After 2 minutes, was consistently going up 15 degrees a minute until 7 minutes. it then slowed down to 10 degrees a minute, and between 9:30 and 10 minutes I went over 160F and my thermometer was over range. Burn ended at 11 minutes. That is, the light coming from the cone went to almost nothing. Pretty much the same burn time as the previous test. No simmer sounds, likely got to 170F or so. That does say if the water started at 70F one could get a simmer out of 4 cups and 2 Coughlan’s tabs. Interesting . . .
Picture of ash and leftovers
I guess black on black does not show so well. Here is the ash on a white background (my data sheet)
And if you are not bored to tears yet, hold on for test 3!Feb 15, 2016 at 9:37 pm #3382295
Drum roll . . . . . . . . . . . . . . . .
The third test results. 14 g Esbit tab. 4 cups really cold water, 33F to start. Very similar results. After 2 minutes, the temperature went up about 20 degrees, same as the Couglans. Between 2 and 7 minutes the temp went up about 15 degrees per minute, 77 degrees measured, compared to 72 degrees for the Coughlans. at about 9 minutes the temp stopped going up appreciably, only 7 degrees in the last 3 minutes. I had over ranged my thermometer for the Coughlan’s test during that end time, which is partly why I started with colder water for the Esbit test. Max temp with the Esbit was 156, or a 123 degree rise.
One last data point. Basically zero ash with the Esbit. I mean nothing. Since black on black does not really work, I did not take a picture.
Based on this testing with my setup, I see no reason to buy Esbit and 1.5 so 2x the price. A bit of ash is just not worth that to me.Feb 16, 2016 at 5:39 am #3382308
Unless you use a ton of Esbit it doesn’t make a huge difference dollar-wise.
When I was doing a bunch of testing it added up but now that my Esbit cook kit is dialed in the difference is just pennies per trip.
And around here Esbit is a lot easier to find than the Coghlans tabs, although I haven’t gone out of my way to look for them… maybe more success at hunt/fish-type stores.Feb 16, 2016 at 7:20 am #3382319
Well, I will admit I am a bit of a cheapskate Bob. But I do have a few trips coming up in the next year in a half that are somewhat substantial. This summer is a 10 day Tran Sierra, next summer is ~20 day JMT trip. I figure 2 cooking sessions a day and on Esbit or 2 Coghlan’s per session. I already have bought the Coghlans, 144 tabs for just under $20, so about 27 cents per 2 tabs. Getting Esbit for $7 is a good deal, so those are 71 cents each. The only local place I can buy it is REI, which is $8+ tax a box. It is actually hard to find it for less even on the internet. Ignoring over night and other short trips, about 60 cooking sessions in these two trips. So for the Coghlan’s that is $16.21 and for Esbit $42.50. I will admit you won’t buy a cuben fiber tent with the savings, but it is noticeable I would say.
I can’t find 144 tabs for under $20 presently, it is more like $27.50 on ebay. Still works out to $22.88 for my two big trips vs $42.50. Well, I suppose you could argue $20 for two big trips is down in the noise compared to the overall cost. I would admit that is correct. I am not saying I would never buy Esbit again, but I would say there is really no reason to not buy less expensive and equally performing Coghlan’s, at least for my stove setup.
I will also say this was a fun exercise for me if nothing else. Back to your regularly scheduled programming . . .
Note: just realized its Coghlan’s, not Coughlan’s . . .Feb 16, 2016 at 7:35 am #3382322
I finished a home made cone for a grease pot today(Kmart grease pot with strainer lid and al foil).
Matt, that combination is what is giving you such good results ;-) You’re able to eek out maximum efficiency. Thanks for all the test data………well done!!!!Feb 16, 2016 at 8:36 am #3382328
Matt, Kittery Trading Post is selling a box of 24 Coghlan’s tabs for $2.19. You’ll have to pay shipping, but it is still a good bargain. I picked up 10 boxes before the holidays when they offered free shipping to BPL members. I thought that $ 0.09 per tab was a screaming deal.Feb 16, 2016 at 9:03 am #3382336
Great news Gary! This is back at my <$20 for 144 tab price, even with shipping. With free shipping you are right, that is a screaming deal. Thanks for the tip, although I won’t take advantage of it for a year or so, as I still have 5 1/2 boxes left from my purchase last fall. But I will note this for the next time I need to stock up. If you hear of a free shipping deal again pass it along as that would be a great time to buy some more.
Glad to hear I am not the only one using Coghlan’s.
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