Initially, we did glue our layers under the assumption that unglued layers would shift. Some customers would receive their mattress and wanted it to be softer or firmer. While they would have enjoyed the mattress in a different firmness, their only option was to return the whole mattress as the layers were glued together and couldn't be changed. Additionally, customer feedback showed us one of the primary reasons customers choose a natural latex mattress is because of the purity and lack of harsh chemicals. We felt using as many as 4 cups of glue in each mattress (the amount needed to glue a queen size mattress) did not align with our customers' values, and began our research to build a healthier mattress. After extensive testing, we found 100% natural latex is naturally abrasive, and the layers "grab" each other, which prevents shifting. In fact, you would need to hold your mattress up to a 90 degree angle before seeing any movement at all. Further, a huge advantage to non-glued layers (both immediately when you receive your mattress or years down the road if your comfort needs change) is that if your mattress is too firm or too soft, you can simply exchange a layer of latex to a firmness of your liking vs. returning the whole mattress. With our 100 night comfort guarantee, this can be done with just a flat rate $45 shipping fee.