Low hydrogen electrodes should be stored in their original hermetically sealed containers until needed, or in a rod oven held at 250 to 300°F (120 to 150°C) once opened. Moisture is the enemy of these electrodes, and even a few hours of exposure to humid air can absorb enough water to cause weld defects like porosity and cracking.
Why Moisture Control Matters
Low hydrogen electrodes (E7018, E8018, E9018, and similar classifications) are specifically designed to deposit weld metal with very little hydrogen. Hydrogen trapped in a weld can cause cracking, especially in high-strength steels and thick sections. The coating on these electrodes is formulated to limit hydrogen, but that coating is also highly absorbent. At 70 percent relative humidity or higher, the moisture content of an exposed electrode can climb significantly in just a few hours, defeating the purpose of using a low hydrogen rod in the first place.
The AWS A5.5 specification sets moisture limits for low hydrogen electrodes packaged in hermetically sealed containers, ranging from 0.2 to 0.6 percent by weight depending on the electrode classification. Once that seal is broken, the clock starts ticking.
Sealed Containers: What You Start With
Factory-sealed hermetically sealed containers have the electrodes sitting in a padded plastic tray, wrapped in aluminum foil with the air removed. As long as this seal is intact, the electrodes are ready to use straight out of the can with no preheating or conditioning required. Store unopened cans in a dry area at room temperature, and they’ll hold their low moisture content indefinitely.
Some electrodes come in moisture-resistant packaging rather than hermetically sealed containers. These are sometimes marked with an “R” suffix on the classification. They offer better protection than standard packaging but are not as airtight as a true hermetic seal. The distinction matters because it changes how long you can keep the rods out in open air before they need reconditioning.
What to Do Once You Open the Can
The moment you break the seal on a container of low hydrogen electrodes, atmospheric moisture starts getting into the coating. You have two choices: use them within the allowed exposure window, or transfer them to a heated rod oven.
For standard (non-moisture-resistant) E7018 electrodes, the maximum exposure time outside a sealed container or rod oven is 4 hours under AWS D1.1. Higher-strength electrodes have shorter windows. E8018 electrodes are limited to just 2 hours, and E9018 gets only 1 hour. If your electrodes carry a moisture-resistant designation, those windows extend: up to 10 hours for E7018 and E8018, and up to 5 hours for E9018.
These limits apply regardless of the weather. Even on a dry day, the exposure clock runs the same. A good practice is to pull only what you’ll use in the next few hours and keep the rest in the oven. Check the electrode box itself, as many manufacturers print the specific exposure time right on the packaging.
Rod Oven Temperatures
Once opened, any electrodes you aren’t using immediately should go into a holding oven set between 250 and 300°F (120 to 150°C). This keeps moisture from creeping back in. If welding is suspended for more than 8 hours, all electrodes should come off the machines and go back into the oven.
Portable rod ovens that welders carry on the job serve the same function. They maintain that 250 to 300°F range and let you keep a small supply close at hand without exceeding your exposure time. The key is never leaving rods sitting on a bench, in a toolbox, or leaning against a wall overnight. Even in a shop environment, ambient humidity is enough to compromise them.
Reconditioning Moisture-Damaged Electrodes
If electrodes have been exposed beyond their allowed time, they can sometimes be reconditioned by baking them at a higher temperature. The exact temperature depends on the electrode classification, but the process typically requires one hour at the specified final temperature. Lincoln Electric emphasizes that you should not exceed the recommended redrying temperature and that “several hours at lower temperatures is not equivalent to using the specified requirements.” In other words, you can’t slow-bake your way back to specification.
There’s an important limit here: electrodes can only be reconditioned once. After a single rebake, if they exceed their exposure time again, they should be discarded or downgraded to non-critical work where low hydrogen properties aren’t required. Repeated heating and cooling degrades the coating and can cause it to flake or crack during welding.
For critical structural work, especially anything falling under seismic weld demand categories, electrodes that have accumulated more than 24 hours of total exposure outside sealed or heated storage are disqualified entirely, regardless of reconditioning.
A Practical Storage Routine
The simplest approach is to treat your rod oven as home base. Keep all opened containers in the oven at 250 to 300°F. Pull out only what you’ll weld with in the next couple of hours. Return any unused rods to the oven at the end of a session. Mark or separate any rods that have already been reconditioned so they don’t accidentally go through a second bake cycle.
For job sites without power for a rod oven, plan your electrode quantities carefully. Open only one can at a time, and track how long ago you broke the seal. If you’re working in a humid climate, treat the shorter exposure times as your hard limit rather than pushing toward the maximum. A few dollars of wasted electrode is always cheaper than grinding out and re-welding a failed joint.