Some latex mattress sellers that offer glued latex layers with VOC free glue claim that manufacturers that don't glue their layers -- like Spindle -- have issues wtih the layers shifting inside of the cover.
We can't take responsibility for naysayers. Every story has at least 2 sides. There are plenty of customers who approach Spindle because they prefer to avoid glue. We don't know if there's any danger in the glue most latex mattress manufacturers in this class would use. It is water based made of latex and comes with certification that it's "safe". But that's not why we don't use glue.
Spindle was founded to build great natural latex mattresses and sell them at affordable prices. The design we use -- 3 individual layers -- helps us meet that goal. The logistics of shipping a fully constructed 10" latex mattress would impact our shipping costs and through our pricing model out of wack. Moreover, our King mattress weighs approximately 180lbs. The vast majority of our customers would find that very hard to handle.
With the friction between the layers of latex and the cover binding them together, we see little shifting. You'll find a video demonstration on our website that discusses this very matter. Please note that the shifting and bunching can happen to any mattress glued or non-glued to memory foam or innerspring to sewn shut. It depends on how the materials are constructed and attached together. In the end, ours tends not to shift significantly and not cause issues for most people. Sometimes, people may unzip the cover and reposition the materials inside of the mattress. For some this can be an advantage compared to a sewn shut mattress where you can't do anything if the materials shift and bunch.
We will never say never. Everyone is different and sensitivity is subjective. The mattress cover fits appropriately but not taught. What you use for sheets and a mattress protector may mitigate or increase the risk of bunching or shifting. As with all things, it depends and the answer isn't black and white. The shifting usually isn't an issue, but everyone has varying experiences on any mattress. We don't have any records of a complaint, but it doesn't mean that it could happen in the future.