Bend-over test revealed Lululemon's defect

Lululemon (LULU) shocked the yoga world when it revealed on Monday that some of its popular black Luon pants were too sheer, leading to see-through bottoms. 

But another surprise was revealed by CEO Christine Day on a Thursday conference call, when she noted that the defect with the pants weren't noticed until customers put on the pants and bent over. 

Remember, these are yoga pants. 

It's not clear why the company didn't ask a few employees to don a pair and try the basic butt-in-the-air downward dog pose before shipping them out to stores. That would have certainly revealed the pants' defects, rather than letting customers find out they were baring all in the middle of their Bikram classes.

"The truth of the matter is the only way that you can actually test for the issue is to put the pants on and bend over,” Day said on the conference call. "Just putting the pants on themselves doesn’t solve the problem. So it passed all of the basic metric tests, and the hand feel is relatively the same. So it was very difficult for the factories to isolate the issue, and it wasn’t until we got in a store and started putting it on people that we could actually see the issue.”

Day said the company was "pursuing several hypotheses" to figure out what went wrong with the pants. 

The recall affected 17% of all the women's pants sold in Lululemon's stores, as reported by my colleague Jonathan Berr. The company's shares have declined 15% this year through Thursday. 

The fabric, called Luon, is made of 86% nylon and 14% Lycra and has a reputation of wicking away moisture when you sweat, according to Business Insider. 

"This is not the Luon we have come to love," Day said on the call. 

While she said the company is putting in stricter quality-control measures, it's not clear whether fans will stick with the retailer. After all, competitors such as Gap's (GPS) Athleta sell a similar type of pants. Lululemon also said it will have a shortage of the impacted style. 

Asked repeatedly by analysts about what went wrong, Day noted the fabric "has to be engaged in a four-way stretch for the sheerness to appear. So it’s a very complex thing to test for."

Maybe, but most yoga fans would tell you that a child's pose is, well, child's play.

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