I saw that the ILD ranges for 100% natural Dunlop by Mountain Top and Arpico are quite different (ex. Mountain Top soft 11.5-14.5 and Arpico soft 19-21; Mountain Top medium 17.5-20.5 and Arpico medium 24-26). Both ranges are for 3" layers. Arpico’s ranges are consistent with guidelines you posted in April 2013. Would the fact that Mountain Top utilizes the continuous pour method or zoning have any bearing?
Thank you for a wonderful, informative site!
Hi Bluebutterfly,
There are several methods of measuring ILD used around the world by different manufacturers or for different materials and the method that Mountaintop uses is different from Arpico and many other Dunlop manufacturers that pour 6" cores in a mold so it’s indirectly related.
Most Dunlop manufacturers test ILD using a 6" core (or whatever the thickness of their core is). The ILD rating is then taken at either a 25% compression or at a 40% compression. The most common measurement for cores in North America is 25%. If the core is 6" then 25% would be 1.5" and 40% compression would be 2.4".
Mountaintop uses a 4" core to test their ILD’s so that the number of inches the material is compressed is less than a 6" core. A 25% ILD rating would compress the core 1". A 40% ILD rating would compress the core 1.6".
The greater the number of inches the ILD rating requires for the measurement, the higher the ILD number will be.
I believe that Mountaintop provides both 25% and 40% ILD measurements taken on a 4" core and the 40% rating would probably be closer to the 25% rating on a 6" core (although they still wouldn’t be the same).
In some cases when ILD measurements don’t use the same method it’s probably more accurate to go by the seller’s soft, medium, firm terminology instead of ILD even though different manufacturers may also have different ideas of what soft, medium, and firm should mean.
In some cases the person you are buying from may have direct experience with both the Mountaintop continuous pour latex and molded Dunlop and if they have compared them directly they may be able to give you a good sense of how they compare based on their personal experience.
Phoenix