Shimon,
Here's what Lincoln Electric has to say about drying electrodes. You'll get the gist of it here...
Here's the link to the actual article where the charts will make more sense (they didn't copy and paste very well here). You'll notice that the ol' fridge with the light on isn't going to get the job done... (but it certainly doesn't hurt anything!)
Storing and Re-drying Stick Electrodes
Electrodes for Shielded Metal Arc Welding (SMAW) or stick electrodes must be properly stored in order to deposit quality welds. When stick electrodes absorb moisture from the atmosphere, they must be dried in order to restore their ability to deposit quality welds. Electrodes with too much moisture may lead to cracking or porosity. Operational characteristics may be affected as well. If you've experienced unexplained weld cracking problems, or if the stick electrode arc performance has deteriorated, it may be due to your storage methods or re-drying procedures.
Follow these simple storage, exposure and re-drying techniques to ensure the highest quality welds, as well as the best operational characteristics from your stick electrodes.
Storing Low Hydrogen Stick Electrodes
Low hydrogen stick electrodes must be dry to perform properly. Unopened Lincoln hermetically sealed containers provide excellent protection in good storage conditions. Opened cans should be stored in a cabinet at 250 to 300ï½°F (120 to 150ï½°C).
Low hydrogen stick electrode coatings that have picked up moisture may result in hydrogen induced cracking, particularly in steels with a yield strength of 80,000 psi (550 MPa) and higher.
Moisture resistant electrodes with an "R" suffix in their
AWS classification have a high resistance to moisture pickup coating and, if properly stored, will be less susceptible to this problem, regardless of the yield strength of the steel being welded. Specific code requirements may indicate exposure limits different from these guidelines.
All low hydrogen stick electrodes should be stored properly, even those with an "R" suffix. Standard EXX18 electrodes should be supplied to welders twice per shift. Moisture resistant types may be exposed for up to 9 hours.
When containers are punctured or opened, low hydrogen electrodes may pick up moisture. Depending upon the amount of moisture, it will damage weld quality in the following ways:
1. A greater amount of moisture in low hydrogen electrodes may cause porosity. Detection of this condition requires x-ray inspection or destructive testing. If the base metal or weld metal exceeds 80,000 psi (550 MPa) yield strength, this moisture may contribute to under-bead or weld cracking.
2. A relatively high amount of moisture in low hydrogen electrodes causes visible external porosity in addition to internal porosity. It also may cause excessive slag fluidity, a rough weld surface, difficult slag removal, and cracking.
3. Severe moisture pickup can cause weld cracks in addition to under-bead cracking, severe porosity, poor appearance and slag problems.
Re-drying Low Hydrogen Stick Electrodes
Re-drying, when done correctly, restores the electrodes' ability to deposit quality welds. Proper re-drying temperature depends upon the electrode type and its condition.
One hour at the listed final temperature is satisfactory. DO NOT dry electrodes at higher temperatures. Several hours at lower temperatures is not equivalent to using the specified requirements.
Electrodes of the E8018 and higher strength classifications should be given no more than three one-hour re-dries in the 700 to 800ï½°F (370 to 430ï½°C) range. This minimizes the possibility of oxidation of alloys in the coating resulting in lower than normal tensile or impact properties.
Any low hydrogen electrode should be discarded if excessive re-drying causes the coating to become fragile and flake or break off while welding, or if there is a noticeable difference in handling or arc characteristics, such as insufficient arc force.
Electrodes to be re-dried should be removed from the can and spread out in the oven because each electrode must reach the drying temperature.
Re-Drying Conditions - Low Hydrogen Stick Electrodes
Condition Pre-drying Temperature(1) Final Re-drying Temperature E7018, E7028 E8018, E9018,
E10018, E11018 Electrodes exposed to air for less than one week; no direct contact with water. N/A 650 to 750ï½°F
(340 to 400ï½°C) 700 to 800ï½°F
(370 to 430ï½°C) Electrodes which have come in direct contact with water or which have been exposed to high humidity. 180 to 220ï½°F
(80 to 105ï½°C) 650 to 750ï½°F
(340 to 400ï½°C) 700 to 800ï½°F
(370 to 430ï½°C) (1) Pre-dry for 1 to 2 hours. This will minimize the tendency for coating cracks or oxidation of the alloys in the coating.
Storing and Re-drying Non-Low Hydrogen Electrodes
Electrodes in unopened Lincoln cans or cartons retain the proper moisture content indefinitely when stored in good condition.
If exposed to humid air for long periods of time, stick electrodes from opened containers may pick up enough moisture to affect operating characteristics or weld quality. If moisture appears to be a problem, store electrodes from the opened containers in heated cabinets at 100 to 120ï½°F (40 to 50ï½°C). DO NOT use higher temperatures, particularly for electrodes from the "Fast Freeze" group.
Some electrodes from wet containers or long exposure to high humidity can be re-dried. Adhere to the procedures in the following table for each type.
Re-Drying Conditions - Non-Low Hydrogen Stick Electrodes
Stick Electrode Electrode Group Final Re-drying Temperature Time E6010: Fleetweld 5P, 5P+
E6011: Fleetweld 35, 35LS, 180
E7010-A1: SA-85(1)
E7010-G: SA-HYP+(1)
E8010-G: SA-70+(1), SA-80(1)
E9010-G: SA-90(1) Fast Freeze - Excessive moisture is indicated by a noisy arc and high spatter, rusty core wire at the holder end or objectionable coating blisters while welding.
Re-baking of this group of stick electrodes is not recommended.
Not Recommended N/A E7024: Jetweld 1, 3
E6027: Jetweld 2 Fast Fill - Excessive moisture is indicated by a noisy or "digging" arc, high spatter, tight slag, or undercut. Pre-dry unusually damp electrodes for 30 - 45 minutes at 200ï½°F to 230ï½°F (90 - 110ï½°C) before final drying to minimize cracking of the coating. 400 to 500ï½°F
(200 to 260ï½°C) 30 - 45
minutes E6012: Fleetweld 7
E6013: Fleetweld 37
E7014: Fleetweld 47
E6022: Fleetweld 22 Fill Freeze - Excessive moisture is indicated by a noisy or "digging" arc, high spatter, tight slag or undercut. Pre-dry unusually damp electrodes for 30 - 45 minutes at 200ï½° - 230ï½°F (90ï½° - 110ï½°C) before final drying to minimize cracking of the coating. 300 to 350ï½°F
(150 to 180ï½°C) 20 - 30
minutes (1) Pre-dry for 1 to 2 hours. This will minimize the tendency for coating cracks or oxidation of the alloys in the coating.
Using longer drying times or higher temperatures can easily damage the electrodes. For drying, remove the electrodes from the container and spread them out in the furnace because each stick electrode must reach the drying temperature.
