The training pants study

I’ve been meaning to write this post for ages, but I started Fancy New Job last week (a part-time gig as a programmer at Biomatters, which I’m hoping will turn into a full-time thing if all goes well, because it’s basically my dream job), and I’ve been knitting and frogging and sewing (of all things!) and unpicking a LOT, and getting test knitters to go over a pattern, and then Tommy was sick twice last week at well-spaced intervals which meant he was home, but not actually sick (and therefore full of beans) every day that I wasn’t working. Which is to say, I’ve been busy. In the meantime, I’m less upset about our daycare’s annoyingly understandable lack of support for our toilet training agenda. Tommy will learn to use the toilet no matter what we or they do, I suspect, and seems to be pretty much still on course while he’s at home.

So as of my last (much more upset) post the daycare had just laid down the law and said that they won’t accept any cloth training pants, at least until the allegedly more absorbent pants we ordered arrived. I thought I’d test whether the ones I ordered really were more absorbent than the others (and how they all stacked up against disposables, represented here by Pull-Ups).


The experiment:[1] Immerse a pair of clean training pants in 750 ml of water and wait a bit (i.e. momentarily deal with screaming children as necessary). Remove them and squeeze gently, then weigh how much water they absorbed.

What am I trying to prove? What I want to prove (because I have an agenda) is that cloth training pants are more effective for toilet training. There’s a notion floating around the cloth diapering community that if kids feel comfy and dry all the time they won’t be as inclined to use the toilet. As far as I can tell, this is entirely anecdotal, but I’ve definitely noticed that Tommy seems to pee more often in his Pull-Ups than in cloth training pants.[2] There are so many other factors, of course: he only wears Pull-Ups at daycare, where he’s less inclined to use the toilet. In any case, I guess I’m just interested in exploring whether disposable training pants are considerably more absorbent than cloth, and how well the training pants I just bought a bunch of perform compared to other cloth pants.

Known issues: Steffen pointed out that I should be doing multiple replicates. I agree, but I think there are other issues. First, some training pants have absorbent fabric outside the PUL layer[3], so they’ll absorb more when immersed than they would be able to when a child pees in them. I’ll mention this more in reference to particular results. Second, this is totally unscientific! I should be timing how long I immerse the pants, and have some reproducible way of squeezing excess water out. But well. This will give a rough idea of how much different training pants can absorb.


Water Absorbed Size Used Notes
Bambino Mio 179 g Size 2 (29–35 lbs) [a]
Best Bottoms 104 g L (30–40 lbs) [b]
Tots Bots 105 g Size 2 (30–34 lbs)
Bummis 197 g L (30–35 lbs)
Blueberries 203 g L (32–42 lbs) [a]
Pull-Ups 557 g 30–40 lbs
  1. Bambino Mio and Blueberries values are too high, for the reason I mentioned above: the outer layer, which is unlikely to actually absorb pee, and if it did it would certainly wick into clothing, is very absorbent.
  2. The Best Bottoms value is sort of too low: The absorbent part of these pants snaps out, so I just tested that instead of the whole pants. Which is to say it’s more accurate than, say, Bambino Mio and Blueberries, but this makes them look like they’re less absorbent when actually they’re probably effectively as absorbent as Blueberries and more than Bambino Mio.

Just as a note, I also tested a pair of size 2-3 years undies for comparison… they absorbed a measly 24 g of water. So.


Like many actual scientific results, these results don’t mean as much as I’m going to claim they do.

In other words, disposable training pants are insane! Holy crap, that’s a lot of pee before your kid starts to feel wet (they actually felt totally dry inside, but they were a lot bulkier after they came out of the water). So if feeling wet is at all relevant for encouraging kids to use the toilet, Pull-Ups can’t possibly be helpful in this regard. I can absolutely see why daycares love them.

The director of our daycare said that Pull-Ups have some kind of endothermic reaction when they get wet (he didn’t say endothermic, of course; they feel cold). He claimed that this is way less comfortable than the warm ‘n’ wet feeling they’d have in cloth training pants, but a) the cool feeling lasts for a very short period of time, and it’s not that cold, and b) there’s no way it’s comfortable to have a warm, wet crotch. I think little kids have a pretty high tolerance for being uncomfortable, so perhaps cloth training pants don’t actually do much to encourage toilet training, but there’s no way the endothermic gel in disposable training pants is more effective.

On the plus side, I think the training pants I ordered are pretty absorbent compared to other cloth pants. But I won’t be surprised if we make our daycare shit list again when they arrive.

  1. The experiment I’d like to do: I’d like to find a few thousand toddlers and assign them to different treatment groups for the purpose of toilet training using different styles of training pants: disposable training pants, very absorbent cloth training pants, less absorbent training pants. I’d ask the parents to record when the kids reached different toilet training milestones, and look at whether there were significant differences between groups. I’ve thought about other details, but this could get very long and boring if I went into it. This experiment will never be done. I suppose I could Google whether it already has been, but there isn’t a whole lot of science done on toilet training.
  2. Even if we go for a very, very long walk and I forget to make him use the public toilet at the library, then we continue walking all the way home.
  3. For those who aren’t as obsessed with cloth diapering: PUL = polyurethane laminate, the waterproof layer of the diaper or pants.

5 thoughts on “The training pants study

  1. Ok, this study is hilarious. You lost the opportunity to pour blue liquid into the diapers though, as all good pad commercials do.
    Biomatters! They are the best. I lived and breathed Geneious for about six months last year, curating genomes. Congratulations!! I am sure they will decide to keep you and also move you to full time because you are excellent.


    • I was picturing the blue liquid at one point! And then the nicely manicured hand folding the pad to show how not-wet it is when it’s done.
      I’m pretty excited about Biomatters, but Geneious is HUGE and it hurts my brain to try to navigate it. I spent all day yesterday trying to do something that I should have been able to finish in an hour, and I was exhausted afterwards.


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