It’s starting to get hot here in the desert getting cupping problems. As always I flatten both sides, and start carving. On longer carves 1.5 hrs, I noticed that my boards are cupping. Both edges are rising and I am getting undesirable depths and line thickness. In those raised areas. I cannot clamp down as I am carving most of the surface. Anyone have suggestions/experience? I thought about using double sided tape but not sure it will hold the wood down.
Cesar - are you sure the cupping is related to the low humidity and not e.g. internal tension in the wood, or unevenly dried stock?
Are you letting the stock acclimate before and during the prep-phase? Are you selecting stock that is naturally resistant to cupping (species/cut/grain orientation)?
To your question: I think tape and super glue or e.g. a vacuum table would help BUT when you release the clamping pressure, isn’t the wood going to cup anyways? ( Some cupping in the finished carvingmay or may not be acceptable in your application.)
-Mark
Acclimate 3 days before flatten. Then let it sit for 2 nights for the most part. All I have is Blue or Orange stores so mostly Plain-sawn available. Nearest nice wood store is 1.5hrs away. Stock is a problem. Got it double sided tape for now
What a drag. How about sinking some hole in the waste board and screw into the stock from below?
If worried about hitting screws: Drill holes in stock to take wooden dowel pins, glue dowel pins into the stock, place dowel pins through holes in the waste board and pin the dowels from below by drilling hole through the dowel and securing with a wedge…easier done than typed.
Thought about laying it down on bench cookies. And securing the sides. Anyways ruined it regardless. Surprisingly I let it sit on the machine over night (double sided tape) and there was no warping, not sure if the temperature drop helped or if it was the double sided tape. But it’s ruined regardless. 
I recommend the blue tape and super glue method. I used to use the foam double sided tape, but found it was not a consistent thickness or lifted over time. Maybe other types would be different - I’ve heard carpet tape works really well, but makes removing the part very difficult.
-Tom
Bring wood into your shop and let it sit for 2 weeks. Allow air to get to both sides so it gets accustom to your shop. Don’t let it sit overnight on the spoil board unless you are sure the wood’s moisture has equalized to your shop. Otherwise the moisture will leave or enter (if your shop is drier than the wood) at different rates.
I’ll try that. The double sided (carpet) tape I used did the trick but I am worried about thickness inconsistencies. So I’ll use the superglue method. Sitting on the spoilboard 2-3 hrs while flattening Roughing and detail carves, it does cup. However this last one cuped a bit and resettled after letting sit on painters triangles over night.