We recommend setting your glue gun to 350°F (190° C) as a general rule. As the glue is dispensed, you should see some smoke whisping off the melted glue. Glue that is bubbling indicates the glue gun is too hot which will prevent proper glue tab adhesion.
Adjustments to the temperature may be needed based on the specific type of glue used, the age of the glue gun as well as the environmental conditions. All Keco recommended glues have a recommended temperate setting of 350°F which has been extensively tested to yield the best adhesion. For other glue sticks, consult the manufacturer for recommended temperature settings if you experience poor adhesion.