Mattress U seems to be the goto site when searching for the best information on the quality of mattress construction. When researching Sealy mattresses (after finding one comfortable in a store), I was saddened to find links referencing Sealyâ€™s unwillingness to share densities (an experience I shared). However, I found several approaches that let me calculate approximate densities and am sharing the process and results in hopes that the information is useful to others.
First some background so you can apply the numbers to your case. Sealy has (at least) 3 memory foam mattress lines. Since my research was on a Plush, Iâ€™m referencing those models, but most of the math will apply to other firmness once you sort out the line carried by a retailer:
 â€śConformâ€ť line sold by typical retailers (1" SealyCool Gel, 2.5" ComfortSense, 7.5" SealySupport)
 â€śLaZeâ€ť (Big Lots) or â€śMemory Foam Mattressâ€ť (Mattress Firm) (3" SealyCool HD Gel, 2" SealyCushion, 7" SealySupport)
 â€śTo Goâ€ť mattress in a box sold direct and by e.g. Wayfair (3" CopperChill, 4" Advanced Comfort, 5" UltraSupport).
When it comes to density, I found two exceptions to the â€śno dataâ€ť rule:
 Big Lots actually advertises the SealyCool with GraphICE as a 2.5lb foam
 Wayfair lists its top layer as 3lb. The image is actually a â€śTo Goâ€ť mattress and the layer sizes all match.
I was also able to work out very good numbers for the To Go line. In this case, there are four different styles that combine different quantities of each foam. Amazon has a great comparison table and is also the source of my weights (for king):
 0" Memory Foam / 2" Advanced Comfort Foam / 6" Base Foam is 58 lb
 2" Memory Foam / 0" Advanced Comfort Foam / 6" Base Foam is 66 lb
 2" Memory Foam / 3" Advanced Comfort Foam / 5" Base Foam is 79 lb
 3" Memory Foam / 4" Advanced Comfort Foam / 5" Base Foam is 97 lb
If you solve the simultaneous linear equations, we get the following (very reasonable) values;
 CopperChill Memory Foam at 11 lb per inch or ~3 lb density (which matches the Wayfair density)
 Advanced Comfort Foam at 7 lb per inch or ~2 lb density
 UltraSupport Base foam at 7 lb per inch or ~2 lb density
The last way to estimate density is to find a topper of the same material with a published weight. A 3" king topper is nice because it works out to 10.6 cu. ft. of material so the conversion to standard density (lb per cu. ft.) is pretty simple: All my math will multiply/divide by 10 (vs 10.6) so the weights will be a hair high but close enough.
 ComfortSense is listed at 30lb
 SealySupport is listed at 22.6lb, but this is for a Memory Foam topper NOT base foam.
 SealyChill is listed at 31lb
 PerfectChill is listed at 45.9lb
Dividing by 10, the foams range from ~2.3lb to ~4.6lb. To crosscheck all of these values, I also looked at the total weight of full constructed beds:

On Amazon, the Conform bed is listed at 50lb, but this seemed low so I double checked the weight and found a 61lb weight on MattressShowRoom.net and US Mattress. If we assume the Conform uses the same 2.5lb SealyCool foam advertised by Big Lots for the 1" layer (8lb) and the 3 lb topper weight for the 2.5" layer (25lb total), a 61 lb king weight leaves 28lb for 7.5" of base foam or about a ~1 lb foam. This seems unrealistically low so I think it likely that the ComfortSense layer is not 3lb. If I use a 2lb layer (20lb), the base foam would be 33lb or 1.3lb foam â€“ consistent with low quality foams.

The 99lb weight of the LaZe king (at BigLots) really doesnâ€™t make sense and US Mattress doesnâ€™t have a weight on its comparable bed. If we assume the top and bottom foams (of the same names) are the same as the Conform, this bed appears to use 7" of the 1.3lb support foam (30lb total) and 3" of 2.5lb SealyCool (25lb), but that that leaves an implausible 44lb for the last 2" of SealyCushion (nonmemory) air foam (i.e. a ~6.6lb density). The shipping weight must be incorrect and, given that the math works best with 2lb transition foam in the other two models, this seems most likely here as well.
In summary, my best estimates are:
 â€śConformâ€ť line with 1" 2.5 lb SealyCool Gel, 2.5" 2lb ComfortSense, 7.5" 1.3 lb SealySupport
 â€śLaZeâ€ť line with 3" 2.5 lb SealyCool HD Gel, 2" 2lb SealyCushion, 7" 1.3 lb SealySupport
 â€śTo Goâ€ť mattress in a box with 3" 3lb CopperChill, 4" 2lb Advanced Comfort, 5" 2lb UltraSupport
At minimum, this highlights the relatively low durability of the foam in these models. Hopefully this is helpful to others.