We had a live webchat at 9pm on Monday 3rd April looking back at the Hydroxyl Apatite project.
Main findings
| Sophia | What do we think we’ve learned from the experiments then? TBH, I feel like I know less about HA and nappies now than I thought I did before! |
| Iona | We found HA again on some test nappies which was good. But we also found calcium carbonate which has confused the issue |
| Sarah | and the zinc thing too |
| Iona | Yes, the zinc was another new and interesting finding. I was so disappointed for the dip and dry testers that nothing was found on those samples! |
| Sophia | I know! And I felt bad for the people who’d dealt with the wee smelling boosters for a month, to no avail. |
Experiments don’t always work like we expect
| Sophia | Iona- you did a science PhD, was there a lot of doing experiments and finding nothing? |
| Iona | Absolutely. At times it felt like my entire PhD was about finding nothing! And the experimental results you do get, just lead to more possibilities. So I’d say this is fairly typical! But they inspire and challenge you to do the next set of experiments. |
| Sophia | Even though I have a science degree, most of my education involved doing ‘practicals’ rather than real experiments. So maybe it trains you to think that you will get results every time. |
| Iona | Ah yes, the difference comes when you design your own experiment, rather than follow a tried and tested method! |
| Iona | My undergraduate project also didn’t work! |
| Sophia | Also, science documentaries and news stories are all about the times they DID find something. False advertising! |
| Iona | The news don’t want to hear about what you didn’t find! And its actually a big issue in science. People don’t publish null results, so the next group waste money repeating experiments that don’t work. But who wants to say ‘I spent the last 5 years doing X and it didn’t work’ |
| Sophia | Ha! |
Why didn’t the experiments work?
| Sophia | If we could do more experiments, what would they be? |
| Sarah | I suppose the no results lead you to creating a trial or experiment that does have a positive answer so you can get the glory of finding out something new? |
| Iona | And we did find things HA, Calcium Carbonate, Zinc, a trend towards an increase in pH during dry bucket. Sarah- did you do the pH tests or dip and dry experiments? I’d be interested to see what would happen with dip and dry, if we used a combination of urine and detergent together but I’m less sure I’m volunteering to smell it |
| Sophia | And maybe urine can form HA, but it needs to be urine with a high calcium content or high phosphate content (or both!) and we just didn’t happen to have that with the children who’s wee was used. |
| Sophia | So maybe we would need to test a lot of wee to find the right conditions. |
| Nicola | Having a little read through the chat so far, I was pretty disappointed we didn’t get the results we wanted! I thought perhaps we would get HA from the dip/dry experiments |
| Iona | I really wanted the dip dry to work |
| Iona | I wonder if toddler wee contains less calcium because they are partly weaned? |
| Iona | The calcium carbonate that Shirley Technologies found is an interesting side angle |
| Sophia | We could dip boosters in adult wee? |
| Nicola | I wondered about the toddler wee not being right for the nappies while doing the experiment but then forgot to ask about it! I figured it would be quite difficult to get babies wee unless people were doing EC |
| Nicola | Not keen on that one Sophia! |
| Iona | Much easier to get samples of adult wee! What effect would last nights glass of red wine have? Or do we need to drink Bailey’s to increase calcium? |
| Nicola | I think more wee testing would be helpful, but perhaps with younger babies, breastfed and formula fed to check if one would be more likely to have HA or Calcium Carbonate |
| Sophia | I volunteer for that one! (The drinking baileys) |
| Nicola | Haha! |
Wanted: baby wee expert
| Iona | We never managed to get a baby wee expert to talk to us unfortunately. I emailed about 10 of them! They probably thought i was mad! | |
| Nicola | I didn’t know there was such a thing as a baby wee expert! | |
| Iona | I emailed infant urology consultants. Doctors who deal with kidney issues etc. But they are probably too busy | |
| Nicola | Good idea Iona, that would have been helpful had they been able to join in. |
Why is there more hydroxyl apatite in certain nappies?
| Sophia | I still find it really strange that so many of our first lot of test nappies had loads of HA, but then the more recent lot some of them had HA, but none had as much. | |
| Iona | Were they as ‘problem’ as the first lot? | |
| Sophia | Maybe not as problem as the first lot | |
| Nicola | Am I right in thinking the first lot of nappies with the HA were pre-loved so unknown history? | |
| Sophia | I think some of the first lot were preloved, but some weren’t. | |
| Iona | It was interesting that the highest HA/CC was found on a wipe, not a nappy | |
| Iona | 15.6%, which is getting close to the results from last time | |
| Sophia | Summary of the results and washing history of last year’s test nappies https://nappysciencegang.wordpress.com/2016/11/06/apatite-for-destruction-the-hypotheses-so-far/ | |
| Nicola | Do we know if the wipe was stored wet before use? That might indicate it’s the water causing the HA as opposed to the wee or detergent | |
| Iona | That is an interesting question | |
| Sophia | Good question |
Wipes and wet pails
| Iona | I was thinking that the wipe will have been drenched in water and then stored, but of course it may have been stored wet before use too. And ASR did claim to have very hard water | |
| Nicola | I keep my wipes damp in a tub ready to use, I thought a lot of people did the same rather than wet as needed so it would make sense. And Jennifer told us her student created HA from very hard water didn’t she? | |
| Sophia | Yes, although they had also added phosphate | |
| Nicola | Ah ok | |
| Iona | Do we know where ASR lives and if phosphate may be added to her water? | |
| Nicola | Lack of scientific knowledge here, am I right in thinking phosphate is like salt? | |
| Iona | Nicola- I think you are right, most people store wipes wet. I forget, as we store them dry and wet as we need them. | |
| Nicola | Or what would cause phosphate to occur naturally perhaps? I guess everyone does things a little differently Iona, would depend on your facilities at home and what’s easiest! | |
| Sophia | (BTW, ASR is actually AJR, Ian misread her writing) | |
| Iona | Oh yes, I forgot | |
| Sophia | I think the wipe had 15% ash, but it was more calcium carbonate than HA. So it could be that how she stored the wipes or something made CC more likely to form. | |
| Nicola | Perhaps she used something other than just water too? We will need to ask her and include it in the write up | |
| Sophia | Good thinking | |
| Iona | Sophia- did you get her postcode? Maybe we could look up her water supplier? And there was the calcium hydroxide that CCI found formed at low calcium concentrations. I wonder what determines whether calcium hydroxide, calcium carbonate, or HA forms? | |
| Nicola | Good question Iona | |
| Sophia | I’ll check | |
| Iona | I’m guessing you will check postcode Sophia, rather than having a magic answer to the chemistry question! Maybe if she took part in pH experiment? Nicola or Sarah- did you do the pH or dip dry experiment? | |
| Nicola | I did PH and dip dry. I am in very soft water area though | |
| Sophia | The form for submitting the nappies was the one Grace did and I don’t have access to the answers | |
| AJ | I’m here, sorry I’m late 3 year old up | |
| Sophia | Hi AJ! We are just discussing your wipe | |
| AJ | Will just try and read back. Saw fb quickly. My wipes are stored dry before use and wet (for a good few days) after use | |
| Nicola | That’s interesting, I thought storing wet first would have caused the HA but obviously not! | |
| Iona | AJ- do you use any oils on the wipes? | |
| AJ | I wet as I breed it on the day of using. I’m in a ridiculously hard water area. It’s a private, borehole supply | |
| Kate | Hi. Sorry so late. Rubbish internet here. | |
| Nicola | I don’t know why I think that… after wiping there can’t be much wee on the wipe to be reacting with the water? | |
| Nicola | Did anyone who wet-pailed offer to donate nappies? That might be an interesting experiment | |
| AJ | Mixed re oil. Not on dry wipes but I do on wet ones. It’s cheeky wipe dirty oil | |
| Kate | Did we have any info about how the calcium carbonate presented itself. Was it an exoskeleton like the HA, particles trapped in the fibres? | |
| AJ | Is cc directly linked to hard water? I’m really surprised my nappies weren’t loaded as they were so crusty | |
| Sophia | Kate- Further analysis showed that in all cases the residual material was intimately associated with the fibres of the tested fabric, and formed a skeletal residue when the washing removed the cellulosic fibre. | |
| Kate | I remember that if you use soda crystals calcium carbonate is what you get when it reacts with calcium water hardness ions, which is why I wondered. | |
| Iona | AJ- do you have any idea if phosphate is added to the water in your area? | |
| Kate | Wow so it was a similar form. Does that mean it has formed by crystallising in drying, same as HA, I wonder. |
Crustiness and hard water
| Nicola | AJ- can you describe crusty? Like the way bamboo gets a bit hard then softens up if you rub it or tumble dry, or like crusty that won’t go away no matter what you do? | |
| Sophia | AJ- I guess your nappies were the only ones that had ONLY HA in them. Although it wasn’t as high a proportion as the ones we got tested last year. | |
| AJ | I was disappointed as it leaves more questions than answers | |
| Sophia | I wonder why AJ’s nappies had only HA, but the wipe had both CC and HA, but more CC. | |
| Iona | AJ- I think you said you wash wipes and nappies separately? | |
| Nicola | Oh, I think I read something about limescale and calcium carbonate when I was looking to see what CC was, perhaps it was the machine that caused it | |
| Sophia | It’s strange, isn’t it? If they feel dry and rough, what is causing that, when the HA content is not THAT high? | |
| Iona | Towards the end of last chat I asked if AJ knew if phosphate was added to her water supply? | |
| AJ | Yes I wash separately as otherwise they get too tangled up. Could overdosing of powder be an issue? I always had an overfoaming machine when washing wipes as microfiber reacts strangely in the wash | |
| Iona | AJ- if you wash separately, our theory about urine being important could be flawed | |
| Sophia | Calcium carbonate is what limescale is made of, so if your washing machine was full of limescale, then it looks like there’s lots of CC in your water. | |
| Iona | AJ- does anything else get rough e.g. towels | |
| AJ | Yes everything gets rough. I add softener to everything but nappies and wipes |
Can crustiness be reversed?
| Iona | If it is limescale, then would vinegar remove it? | |
| Sophia | Or citric acid. | |
| AJ | I’ve been reading lots about vinegar! I’ve just bought a stash for cleaning with | |
| Nicola | Experiments to see what removes it?! | |
| Iona | Citric acid was suggested by Prof Darvell as a potential for removing HA | |
| AJ | It did well on my drainer better than I thought | |
| Sophia | Presumably citric acid would work on CC too? | |
| AJ | Can you add it into the wash? | |
| Iona | I assume so, it is a stronger acid than vinegar | |
| Nicola | From nappy lady website: Vinegar has traditionally been used as a nappy soak however many nappy manufacturers including Totsbots, Bumgenius and Bambinex now specify that vinegar, or any soaking agent including Bicarbonate of Soda, Nappisan, bleach or harsh stain removers should never be used as they can corrode the nappy fabric and effectively destroy your nappies. Please note that if any of these products are used on the nappies or accessories it will invalidate any product guarantee. Bamboo is an especially delicate fabric and is particularly susceptible to harsh chemicals. | |
| Iona | Sorry assume so was to the citric acid removing cc | |
| Sophia | Prof Darvell thought citric acid would work better than vinegar because it makes the mineral you remove stick together in clumps (I think he said it’s a chelating agent and I think that’s what that means) | |
| Iona | Yes, he suggested an overnight soak in citric acid and then several hot rinses. For the chelating part, soaking is important ‘no quick rinse’ he said. I think any extreme measures will invalidate warranty | |
| Nicola | A lot of things seem to invalidate the warranty, I suppose if they are already quite bad that may not be a concern though? Just thought it might be relevant | |
| Iona | Very relevant | |
| Nicola | AJ- I’m curious, have you tried to strip by leaving out in the rain to see what that does? | |
| AJ | I leave them out regularly in the summer, not so much in the winter. It’s all our clothes, not just nappies. My little boys jeans stand up in their own! | |
| Iona | oh dear | |
| AJ | More experiments are needed for sure but on what specifically | |
| Nicola | We were saying in the last chat more experiments on wee might be needed. Although with all this talk of your washing I’m thinking more experiments on hard water would be good! | |
| AJ | Interestingly are about to move house and are thinking about getting a water softener would be interesting to compare | |
| Iona | You can read Prof Darvell suggestions for experiment at: https://nappysciencegang.wordpress.com/2017/01/15/ha-solubility-email-chat-with-prof-brian-darvell/ It would certainly be interesting to see if a new nappy went crusty with a water softner installed | |
| Iona | Or if your existing nappies ‘softened’ over time | |
| AJ | I’m hoping anecdotal evidence will say that | |
| Nicola | Ok I need to go now. Night all! | |
| AJ | Shall we call it a day? | |
| Iona | I think we probably should. Goodnight and thank you. |
Summary
- We found hydroxyl apatite and another mineral deposit on nappies we tested.
- We did not manage to create hydroxyl apatite in our experiments.
- There are aspects of infant urine and nappy washing/drying practices that we don’t fully understand that probably affect mineral deposits on nappies.
Nappy Science Gang 