My 7 1/2 year old granddaughter has an extremely hard innerspring twin bed; it is essentially like sleeping on the floor. I would like to soften the bed by getting her a 100% latex 3” topper (unsure whether dunlop or talalay). Does the advice that firmer is better than softer in a sleep surface for a young child still apply to a 7 1/2 year old?
In general yes. While it would depend to some degree on their size and at 7 1/2 years old their preferences may play a slightly larger role (although I would be careful here because children often prefer things that aren’t particularly good for them) … I would be very cautious about choosing something that was too soft for a child as long as they are still growing and developing into their more adult proportions.
Because of the supportive nature of latex compared to other types of foam … you would probably be “safe” with something a little bit on the softer side of medium but I wouldn’t go any softer than that.
Just as a clarification as well … you won’t find a latex topper that is anything but “100% latex” because synthetic latex and natural latex are both equally “latex”. I’m guessing that you probably meant 100% “natural” latex rather than 100% latex. All the latex you are likely to encounter (Dunlop or Talalay made with either natural or synthetic rubber or a blend of both) will all have been certified by either Oeko-Tex or Eco-Institut for harmful substances and VOC’s (see post #2 here) and I would consider any type of latex to be a “safe” material as well.
There is also more about the different types and blends of latex in post #6 here and there is more about some of the differences between Talalay and Dunlop in post #7 here.
Because of the epiphyseal plate and postural formation that your child will go through, a firmer/medium firm sleep surface will be preferable. If you desire a bit of a softer surface comfort, a latex topper would certainly be an appropriate and desirable choice.
Children often like to choose the softest mattress in the store, as they have less mass and the product feels comfy to them. However, this is one area where the adult need to intervene and provide the proper range of choices for the child.