On Wednesday, May 27, 2020 at 1:58:30 PM UTC-5, wrote:
I use the same domes to display preserved flowers but I am having a different problem. The dome keeps fogging up after a couple of weeks. I am sealing it, and it seems to work, but eventually fogs up again. Any suggestions as to how to fix the problem or knowledge if what is causing the problem? Any help or advice would be greatly appreciated. I am at a total loss...

Well, the plants have a moisture content. I'd suspect that's your source of moisture. This link has a nice video showing two simple techniques for drying flowers and maintaining color.
https://www.google.com/search?q=how+...BO-H_QaHrr1A53

I like the tip of spraying the dried flower with an acrylic sealant, similarly as spraying charcoal sketches with hair spray. It seals the charcoal onto the canvas, paper, or wood.

Charcoal on wood, sealed with hair spray:
https://www.flickr.com/photos/438361...in/photostream

I would suspect you are not drying your plants well enough and/or not sealing them as well as might be. .... unless I'm missing something in your process/processes not revealed in your posting.

Sonny