Hi ikonos,
Dunlop is a little bit tricky to translate to ILD because it is less consistent than Talalay and there is more ILD variation across the surface of the layer than Talalay. It is also firmer on the bottom of a layer than on top to different degrees (that can vary by manufacturer) so if you have a 6" core of a particular density of Dunlop … then a 3" topper cut from the top of the core will be softer than one cut from the bottom. it can also vary depending on which side is up. In other words … it’s best to think of Dunlop in “approximate ranges”.
This is made even more difficult when people are comparing Dunlop to Talalay because ILD is measured as the weight it takes to compress a 6" (in the case of latex) core 25% of it’s thickness using a 50 sq in compressor foot. So if a material takes 30 lbs to compress 25% … then it would be 30 ILD. The only place that Talalay and Dunlop would “match” would be at exactly the 25% compression point and Dunlop would be firmer as it was compressed more than Talalay and softer if it was compressed less. At best … ILD is an approximation … especially with Dunlop. While most Dunlop manufacturers sell their product by density … there are a few who do test for ILD such as Latex Gold here.
Having said all that … I think a reasonable approximation would be …
65 would be considered quite soft for Dunlop and probably in the range of low 20s or lower
75 would be in the range of mid to high 20’s or medium/soft
85 would be in the mid 30’s or medium/firm
95 would be very firm and in the 40’s or firm/very firm
See post #2 here as well for some more specific comparisons that may be helpful.
How firm any of these felt would depend on weight and body type, how much the material was compressed, and where in the mattress the layer was (which affects how much it compresses).
There are also some differences in Dunlop foam formulations that can make a difference and ILD ratings may not be comparable between different types and blends of latex.
Arpico is a high quality dunlop foam manufacturer and you can see the typical densities that they make here from 75 to 95 lbs but they could make a core in different densities as well.
So if it was 65 kg density it would be softer than a typical core (or softer than the “soft” that is listed on their site). If it really was this … then a single core would be soft on top and then get progressively firmer as you sank in deeper. The higher compression modulus of Dunlop can give it “soft on top but good support” properties.
Don’t forget too that thickness and ILD both have a significant effect on the softness or a layer or mattress. For example 3" of 28 ILD Dunlop on a floor would feel very firm (it would fully compress or “bottom out” which means it would get as firm as it could go under the heaviest part of the body) while 6" of the same material would feel softer and 9" of the same material would feel softer yet.
The 90 would be in the range of firm.
In the third store they are probably guessing at the ILD because Dunlop wouldn’t be that exact or have that small a difference. There would be a 4 ILD difference in a typical single Dunlop core much less two separate cores. These are more typically Talalay ILD’s when they are given that specifically and even then even Talalay (from LI anyway) uses an average of 9 separate ILD readings on a core to “rate” it. I would guess that the difference between the cores was more than 4 ILD because it would be unusual for a foam pourer to make cores that were that close together.
Viet Nam is a major latex producer (#5 in the world) but I’m not as familiar with any of the specific companies that make it and it’s less common to see it here. I was even talking the other day with a manufacturer who was working on importing Dunlop from Turkey. Viet Nam produces more rubber than Sri Lanka which is where Arpico and Latex Green are based.
I doubt that Vietnamese rubber of a similar density is significantly different in firmness from rubber sourced elsewhere if they were both natural rubber with no fillers.
I wish I could be more specific but unfortunately it seems that Dunlop ILD is often more the subject of guesswork in many cases and I would tend to trust my body’s perceptions more than someone’s “guess” about Dunlop ILD. While a particular manufacturer could tell you the relative firmness or softness of all the foams they carried and if they also carried ILD rated Talalay their Dunlop rating would be more accurate because they could use the Talalay as a point of reference. Without a reference point or between different manufacturers or outlets where the density isn’t known or who may not use "soft/medium/firm in the same way … it’s much more difficult to make comparisons.
Phoenix