On the PCT, the risk of wildfire is so great that trailside businesses have stopped selling liquid fuels and only sell canisters. On the wet, drizzly AT however, the use of an alcohol stove is not so irresponsible. Many businesses near the AT sell Coleman fuel (white gas) and denatured alcohol by the ounce, and so resupply is easy and can be done as often as you buy groceries.
Some alcohol stove users have started burning a gas-line antifreeze found in gas stations and autoparts stores called HEET. It burns because it contains methanol, but it also contains Xylene and secret proprietary compounds. For environmental and health reasons we strongly discourage the use of HEET. First, you will inevitably spill fuel and you should not be pouring antifreeze into the environment. Additionally, fumes from alcohol stoves enter your food, and who knows what horrible compounds are released from the burning of anti-freeze (a check of its material safety datasheet provided no answers). HEET is bad for you and the environment.
If you cannot find Coleman fuel or denatured alcohol, use rubbing alcohol rather than HEET. Concentrations of 10-20% will not ignite, but concentrations of 70-90% will. Just look for the "flammable" warning on the bottle.
What then is the difference between denatured and rubbing alcohol? Without getting technical, denatured alcohol is ethanol (the stuff in whiskey) that has been poisoned with deadly methyl alcohol
(methanol) to keep us from drinking it. It used as an industrial solvent and cleaning solution. Rubbing alcohol contains isopropyl alcohol, which is less deadly and so can be
used for medical purposes. In practical terms for hikers, rubbing alcohol is cheaper and sold in groceries at smaller quantities, while denatured alcohol is more expensive and sold in hardware
store at greater quantities.
Canister fuel is not only the most responsible choice, it is also the easiest to resupply. Nearly every business that caters to hikers in trailside towns sells 4oz cans from multiple brands. Additionally, hiker boxes are full of semi-used cans. If you want to save money and don't mind carrying a little extra weight (an empty can weighs about 3oz) then you can grab a few nearly-empty cans from a hiker box to tide you over till the next town.
The AWOL guidebook identifies specific locations where fuel is sold, and the type of fuel available.
Canister fuel is so easy to find on-trail we cannot imagine a scenario where you would need to have fuel shipped to you. However, experience has taught that anything is possible on the Trail.
When that unforeseen reason requires a canister be mailed to you, or you need to bounce a can to yourself, you may have a potentially frustrating experience at the post office. Walk into any post office and you are likely to see the poster on the right. According to it, fuel canisters are prohibited in the mail—it’s clear as day right there in the picture.
However, according to USPS regulations posted on the USPS website, you can ship backpacking fuel canisters and non-pressurized liquid fuel if the package is marked “ORM-D” and/or “Surface Delivery Only."
“ORM” stands for Other Regulated Materials. The following two USPS documents are relevant to backpackers trying to ship fuel to themselves. Both documents contain the same information.
1) DMM 601: Mailability
2) Publication 52, Section 342.22a-c
It is a good idea to print out Publication 52 Section 342.22a-c (or keep the PDF on your phone) and bring it with you to the post office in order to trounce stubborn post masters who are unfamiliar with ORM-D guidelines and tell you “no” without double checking the regulations first. Expect at least some clerks at post offices to be unfamiliar with them. In my experience it has been about 50/50.
You may ship more than one canister in the same package. There is no additional paperwork and there are no fees associated with shipping fuel. You also do not need to keep the box open and show the post master the contents of your package. Simply declare the contents of the package and they will write "Surface Mail Only" on the same side of the box as the address. That’s all there is to it.
Here are the relevant excerpts that pertain to isobutane fuel canisters from USPS's Basic Standards for All Mailing Services:
10.12 Gases (Hazard Class 2)
Hazard class 2 consists of three divisions:
a. Division 2.1, Flammable Gases. A material that is a gas at 68°F (20°C) or less and 14.7 psi (101.3 kPa) of pressure. Flammable gases also include materials that have a boiling point of 68°F (20°C) or less at 14.7 psi (101.3 kPa) and that are ignitable at 14.7 psi (101.3 kPa) when in a mixture of 13% or less by volume with air or that have a flammable range at 14.7 psi (101.3 kPa) with air of at least 12% regardless of the lower limit. These conditions must be established in accordance with ASTM E681-85, Standard Test Method for Concentration Limits of Flammability of Chemicals, or other approved equivalent method. The flammability of aerosols must be determined using the tests specified in 49 CFR 173.306(i).
b. Division 2.2, Nonflammable, Nontoxic Gases. A material that does not meet the definition of Division 2.1 or 2.3 and exerts in its packaging an absolute pressure of 40.6 psi (280 kPa) or greater at 68°F (20°C).
c. Division 2.3, Toxic Gases. A material that is poisonous by inhalation and is a gas at 68°F (20°C) or less and a pressure of 14.7 psi (101.3 kPa) or a material that has a boiling point of 68°F (20°C) or less at 14.7 psi (101.3 kPa).
Gases are prohibited in international mail. Toxic gases in Division 2.3 are prohibited in domestic mail. Flammable gases in Division 2.1 are prohibited in domestic mail via air transportation but are permitted via surface transportation if the material can qualify as an ORM-D material (or effective. January 1, 2021, as a consumer commodity material) and meet the standards in 10.12.3 and 10.12.4. Mailable nonflammable gases in Division 2.2 are generally permitted in the domestic mail via air or surface transportation if the material can qualify as an ORM-D material when intended for surface transportation, or as a consumer commodity material when intended for air transportation, and also meet the standards in 10.12.3 and 10.12.4.
An other-than-metal primary receptacle containing a mailable gas may be acceptable if the water capacity of the primary receptacle is 4 fluid ounces (7.22 cubic inches) or less per mailpiece and the primary receptacle meets 49 CFR requirements. Mailable nonflammable and flammable compressed gases are acceptable in metal primary receptacles that have a water capacity up to 33.8 fluid ounces (1 liter or 61.0 cubic inches), depending on their internal pressure. A DOT 2P container must be used as the primary receptacle if the internal pressure is from 140 to 160 psi at 130°F (55°C). A DOT 2Q container must be used as the primary receptacle if the pressure is from 161 to 180 psi at 130°F (55°C). A container with an internal pressure over 180 psi at 130°F (55°C) is prohibited from mailing. Mailable flammable compressed gases are restricted to 33.8 fluid ounces (1 liter) per mailpiece. Mailable nonflammable compressed gases are permitted in individual 33.8 fluid ounce (1 liter) containers that must be securely packed within an outer shipping container. Each mailpiece must not exceed a total weight of 25 pounds.
For surface transportation, packages of mailable gases must be plainly and durably marked on the address side with “Surface Only” or “Surface Mail Only,” and “ORM-D” (or with a DOT square-on-point marking under 10.81.) immediately following or below the proper shipping name (consumer commodity). For air transportation, packages must bear the DOT square-onpoint marking including the symbol “Y,” an approved DOT Class 9 hazardous material warning label, Identification Number “ID8000,” and proper shipping name “Consumer Commodity.” Mailpieces must also bear a shipper's declaration for dangerous goods.