5.1.1.1 ADRENALINA Y NORADRENALINA

One of the key design parameters for knops is that they have greater resilience after compression than down. An experiment was conducted to quantify the dierence in resilience between several types of loose ll:

• Down clusters. • Goose feather.

• Micro-knops (22% high bulk wool, 61% ne wool, 12% micro bre, 5% PLA). • Untreated pure wool knops (27µmwool).

• Underbody knops (50% SK merino, 35% cut WA12 blend, 15% 32 mmPLA) (these are the same

knops used in section 5.3).

5.2.1 Method

The test for resilience after compression is a modied version of the standard bulk test for loose knops [87]1_:

1_{The pre-compression weight and the weight of the light disk are the actual weights used in the experiment, and deviate} very slightly from TM 272 [87] due to wear and tear on the apparatus. Subsequent testers should use the correct weights.

1. 56.7 g of loose ll is evenly spread into a19 cmdiameter cylinder.

2. The ll is compressed under a weight of170.8 g for30 s.

3. The weight is removed for30 s.

4. The above two steps are repeated once. 5. A57.2 g disk is placed on the ll.

6. After30 s, the height of the ll is measured.

7. The disk is left on for a further minute, during which photos are taken. 8. The disk is removed for30 s.

9. The ll is compressed under a weight of2231.0 gfor 2 minutes.

10. The weight is removed for30 s.

11. The 57.2 gdisk is placed on the ll.

12. After30 s, the height of the ll is measured.

13. Post-compression photos are taken.

One of the issues raised with this methodology was its applicability to down clusters and goose feather. To summarise the existing methodologies:

• _{The standard bulk test for knops [87] applies a}60 Papressure to a56.7 gsample twice for30 s, and

then a20 Papressure for30 s.

• The standard bulk test for feather and down [88] applies a 14.8 Pa pressure to a 20 g sample for 60 s.

• This methodology follows the standard bulk test for knops [87], but subsequently applies a770 Pa

pressure for120 s, and then a20 Papressure for30 s.

The key dierence is the use of pre-compression when measuring the bulk, which is retained in this methodology. Feathers and down are never measured with pre-compression, and therefore record higher initial bulks. It was argued (by a potential client) that this methodology does not provide a fair comparison. We disagree with this assertion, for two reasons:

• Down never exists in products in an uncompressed state. As a loose ll that must be trapped in

place within products (usually via quilting), there is always a minimum pressure applied to the down.

• This methodology is intended to give a simple indication of the relative properties of loose lls in

compression-oriented products, such as pillows or sleeping bags (the latter of which must act both as an overbody and underbody product). Under realistic usage conditions, these products are rarely returned to their minimum-pressure state before each use. The exception to this may be pillows, which consumers are aware need to be regularly ued if they contain loose llbut the results obtained by this methodology should correlate with the necessary frequency of ung.

We assert that the inclusion of a pre-compression step therefore gives results that are more reective of user experiences. Furthermore, if the pre-compression step were to be left out, then the down clusters would certainly have a higher initial bulk than the knops, but would also have a higher bulk loss.

5.2. RESILIENCE AFTER COMPRESSION OF VARIOUS LOOSE FILLS 111 Figure 5.1: The various lls pre- (top) and post-compression (b ottom). From left: do wn, go ose feather, micro-knops, 27 µ m w ool knops, unde rb ody knops .

Table 5.1: Pre- and post-compression bulks. The micro-knop bulks are calculated with a sample weight of57.4 ginstead of56.7 g.

Fill type Pre-compression bulk Post-compression bulk Bulk loss (cm3g−1) (cm3g−1) Down 100.9 58.4 42.1% Goose feather 69.5 51.5 25.9% Micro-knops 105.5 83.0 21.3% 27µmwool knops 107.6 88.8 17.5% Underbody knops 104.0 89.8 13.7%

5.2.2 Results

Figure 5.1 shows the various lls after the initial bulk test, and after applying compression. Table 5.1 shows the corresponding measured bulks. The measured bulks for the micro-knops have been adjusted, as they had been bonded an hour previously and were still recovering weight. There was57.4 g in the

cylinder after testing, up from the initially-weighed56.7 g.

It is clearly evident from g. 5.1 that the knops withstand compression considerably better than the down clusters, with 23 times less bulk loss. The knops also perform better than the goose feather, even though their inital bulk was considerably higher. The knops all have approximately the same initial bulk as down for the same weight, indicating that they will exhibit similar loft in end products.

Within the knops, several points are evident:

• The underbody knops have the least bulk loss. This is expectedthey are larger, use a bulkier

wool blend, and have a higher PLA content.

• The micro-knops have the most bulk loss (although only half as much as down), due to a low

fraction of high-bulk wool and a lower PLA content. This blend also results in a softer feel than the other knops; for these two reasons, these knops would be best suited to apparel products.

• The27µm pure wool knops perform better than the micro-knops, which we attribute to the fact

that the bres in the27µmknops are coarser, and store more compressional energy. However, the 27µmknops have no PLA bres to inhibit felting, and so under repeated compression they would

be expected to lose their advantage.