Hi Clawdia,
Latex is a very resilient and elastic material so when you compress it the latex beside the point of compression wants to pull back up and return to its original position with more force than other materials which can pull on the skin so under the point of compression the forces are downward and beside the point of compression along the skin the forces are upward. A more extreme example of shear forces would be the old child’s game of giving someone an indian burn on the forearm where the skin is stretched in opposite directions. Shear forces are forces which act in different directions. Polyfoam and fiber quilting materials have less shear forces (they are less elastic and resilient) which is one of the reasons that some people prefer them with a latex mattress. Very low density or ILD latex would also have less shear forces than higher ILD latex but it’s still a more resilient material than fiber or other types of foam.
A wool topper (see post #8 here) may also work or even a lower cost down alternative (slick polyester) fiberbed may be helpful and it would be less costly to replace than a featherbed. A shredded latex or lanoodles topper may also be worth considering because the latex is in small pieces and the latex beside the point of compression isn’t connected to the latex that is being compressed and can “move” instead of “stretch”.
Phoenix