Hi dmbryon09,
I would be a little suspect of an ILD rating of 16 - 18 ILD for a 4.7 lb density (75 kg/cu meter). It is likely higher.
5.2 lb density (83 kg/cu meter) is also likely to be higher than 28 - 32 ILD.
They almost certainly won’t match the Savvy Rest you were testing. There is more about Dunlop ILD in posts #4 and 6 in this thread.
You are correct with this. In an apples to apples comparison of Dunlop and Talalay of the same ILD … the Dunlop will be firmer for most people (if you compress it more than 25% of its thickness) and there will also be a top to bottom difference to some degree. The ILD will also be affected by which part of the 6" core the 3" topper was cut from.
Latex can be made with either synthetic latex, blended synthetic and natural latex, or all natural latex. Of course there are other compounds used in the raw material or used in the manufacturing of the foam (including soaps, fatty acids, sulphur, gelling agents, antioxidants) but with latex that uses all natural rubber the natural latex content will be well over 90% of the total content and usually higher. Synthetic latex is made from Styrene Butadiene which is similar to natural rubber but not the same chemically (natural rubber is mainly polyisoprene).
This is where buying from a better manufacturer or retailer can make a real difference. As you mention there are some outlets where what you think you are buying and what you end up receiving may not be the same.
This is also true. there is much more about this in post #6 here
[quote]So how can the consumer be sure what we’re getting. especially if buying from a company that sells different kinds of blends?
Who are the major manufacturers of latex mattresses - is there any certifying body or independent information on the composition of various latex products?[/quote]
The most important way a consumer can know about the type and quality of the latex they are buying is by dealing with a reputable retailer or manufacturer with integrity, knowledge, and experience. A list of the ones that sell online, that I know well, and recommend as being among the best quality/value mattresses in the country are in post #21 here. If you are looking for latex layers rather than a mattress … then there is a list of suppliers of latex layers in post #4 here.
There are several reputable testing and certifying agencies for latex of various kinds and the more common ones include Oeko-Tex … Eco-institut … LGA … Greenguard … Eurolatex …and GOLS (a new latex organic standard similar to GOTS).
Hope this helps.
Phoenix