Use lightweight paper to line your envelopes so it won't add too much weight to the card for mailing and it will allow the envelope to close without being too bulky. DSP works well, but I found that regular wrapping paper also does nicely. (See more about that below!)
Also, to keep the envelope from warping from the liner, you only need to put adhesive on the part of the liner that touches the envelope flap. That will hold it in place nicely.
I love SU envelopes because they are a nice weight and feel so smooth. However I ended up buying a bunch of deeply discounted envelopes at a local craft store going out of business. I tried out the liners in those envelopes and they worked well there too! Granted they may not work in all styles of envelopes, but they will work in many.
Now... back to the wrapping paper idea. It worked beautifully! I purchased a goldtone giftwrap at Target for $5/roll. I used it to line 40 envelopes and I still have a ton of paper left for more projects.
|I started with an inexpensive roll of wrapping paper.|
|I cut the paper into strips. Those lines on the back were handy!|
|I put 4 layers of gift wrap under my envelope die and cut.|
|Slide liner into envelope, crease at flap and add adhesive to part on flap.|
|Ta da! A beautiful gold-lined envelope.|