The simple answer is yes. Any exposure beyond recommended atmospheric exposure could potentially lead to the conditions you mention. As you might have already noticed, the flux coating on 7081 is extremely dry so it readily (and rapidly) sucks moisture. For your particular situation (assuming it is your own personal work) your rod oven could be as simple as a tightly sealed (non-flammable)box with a high wattage electric light bulb...

Hi Esa,

I agree with jon20013. Hydrogen has an adverse effects on welds. One source of hydrogen is moisture in the electrode coverings. For this reason, the proper storage, treatment, and handling of electrodes are necessary. The bottom line is that low hydrogen electrodes must be kept dry if they are to perform properly. If unopened hermetically sealed containers are stored under good conditions, low hydrogen electrodes remain dry indefinitely. Opened containers of low hydrogen electrodes should be stored in a cabinet maintained at 250-300 degrees Fahrenheit. When containers are punctured or opened so that the electrodes are exposed to the air for extended periods, or when electrodes are stored in unusually wet conditions, low hydrogen electrodes pick up moisture. The moisture, depending on the amount absorbed, impairs weld quality. A small amount of moisture can cause internal porosity. If the base metal has a high hardenability, even a small amount of moisture can contribute to underbead cracking. A high amount of moisture causes visible external porosity as well as internal porosity. Severe moisture absorption can cause weld cracks or underbead cracking in addition to severe porosity.

There are several good reasons to use a rod oven:

Take a carfull look at the welding code you are using if you are indeed using one. If you are, there is a good chance it might specify that low-hydrogen electrodes are required to be stored in an oven.

Liability is also a reason. If you are welding something for someone else, then if there is ever an issue, you can say you did the right thing.

However, after saying that, I'll take a technical position that might not be to popular, in that the specific application you mentioned, (very thin mild steel), that low hydrogen rods are not necessary, so keeping low hydrogen rods in an oven would not be essential. You would not normally have hydrogen cracking problems if you welded it with a cellulose coated rod, which would normally have more moisture than a low-hydrogen rod that has been stored in reasonable conditions outside of an oven. That said, if I had 7018 rods I was going to be using on 5mm mild steel plate, would I store them in an oven?--- You bet. It reinforces good practice that might save you later.