Panasonic KX-P8410 Operating Instructions Manual page 169

Do not attempt to print on any of the following types of envelopes. These may cause
damage to your printer.
BEnvelopes with clasps, snaps or tie strings (see Figure 1)
BEnvelopes with transparent windows (see Figure 2)
BEnvelopes that will melt, discolor, scorch offset or release hazardous emissions
when exposed to 200 C (392 F) for 0.1 second
BEnvelopes that use encapsulated types of adhesive that do not require moistening
but rely on pressure to seal them
Figure 1
Always test a sample of the envelopes you are thinking of buying. Confirm that the
envelope performs acceptably.
For best printing results
BAvoid printing in high humidity i.e., above 70%.
High humidity may cause the envelope to curl and pick up excess toner.
High humidity may also cause the envelope to seal.
BAvoid printing below 10 C (50 F) with less than 30% relative humidity.
Low temperature with low humidity may cause light printing.
Envelope storage is very important. Store them away from moisture and humid air,
where they can lay flat and their edges won't be bent or damaged. The humidity
should not exceed 70% RH.
Appendix
Figure 2
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