HA in Laundry: Live chat with Ian

In this live chat we spoke to Ian Strudwick about HA and washing Laundry.

Ian is technical manager at Shirley Technologies [the company that tested the nappies for us last year, and discovered the very high buildup of hydroxyl apatite].
He did a live chat with us once before, on his work and on laundry washing in general.
Now he’s come back to tell us what he knows about hydroxyl apatite and it’s build up on fabrics.

Below is the Live chat log from 24th November 2016, 12 nooon
[If you would like to volunteer to tidy it up a bit, please get in touch with Sophia]

Hi Ian. As you can see, the chatroom is open. But I imagine no-one will be here until 12, so you’ve time to grab a coffee or something if you want.
@sophia. Got one, I’m all prepared!
Hi Ian, I make it noon now, so shall we start?
Could you explain a little about yourself?
Hello everyone.
Absolutely. I am Technical Manager and Director of Shirley Technologies, a company of independent testing labs in Manchester and Leeds. We have 4 lab locations and my work crosses each, largely of a technical nature. I am involved in project work and am the public face for such as your group
Hi Kate
Hi Kate and Sophia
And so it’s all there in the write-up of this, can you say a little about the tests you did for us last year and the hydroxyl apatite you found?
Thanks Ian for taking the time to do this chat
Hi Katie
I have been involved in textile testing for 33 years and in technical investigations for the last 21. My skills are multi-disciplinary, I don’t claim to be a chemist per se but I know enough from a textile point of view!
No problem
We investigated the poor absorption performance of terry cloth nappies after multiple uses and multiple washes. We were looking for a reason why absorbency decreased over time for some nappies, requiring a ‘strip wash’
Ian, we’re now really focussed n the hydroxylapatite find. Could you tell us about what you’ve seen of hydroxylapatite in textiles generally over the years?
The original suspicion was some sort of oil deposition acting as a barrier to absorption, or some sort of biofilm. The oil tests were negative and the biofilm high, as expected. However ashing tets isolated teh presence of hydroxyl apatite on the worst affected nappies
@Kate, give him a chance, he was just getting to the HA:-)
Ha ha m I’m too excited about accessing Ian’s brain. Sorry! 🙂
Hydroxyl apatite is an insoluble deposit formed by the reaction between calcium (usually from hard water) and phosphate. This forms calcium hydroxyphosphate – another name for HA
@Ian, how did you know it was HA on the nappies?
By Fourier Transform infra red spectroscopy on the residue from ashing tests
What does that mean, please?
And from research and significant previous of similar issues in the past – not on nappies particularly but on commercially laundered cotton sheets
It is a technique of measuring the transmission and absorbance of infra red wavelengths through prepared samples. The molecules of the samples react in a different way to IR wavelengths and give spectra which allow identification. It is a very definitive technique
So you shine infrared light at it and see how it is absorbed it reflected, and from that you can say the type of substance it is?
Thats a very good summary, yes. The molecules are excited to varying extents at different IR wavelengths which gives a unique spectra
Great, ta.
Does the IR spectroscopy only identify or can it quantify amount as well?
@Ian and is there only one sort of HA? I mean, once you know it is HA, do you know the exact formula and so on? Or are there variations?
No it only identifies single substances. Ashing is used to quantify HA
So you’ve seen it on industrially laundered cotton sheets. We know that phosphates have been banned for a few years in domestic detergents, but they’re still allowed in industrial use, I think.
HA has various different ‘names’ but at the end of the day it is all calcium hydroxyphosphate. However there will be subtle variations based on compound valencies etc
And cotton sheets would be unlikely to be soaked in wee routinely.
Ian, how would those cotton sheets likely be washed? temperature, detergent, etc?
@Ian, yes, tell us more about the sheets! I take it you have found HA buildup on cotton sheets then? What kind of quantity? And was it creating problems with the sheets?
@kate. True. Our experience with sheets was teh reduction in washability caused by deposition of HA from reaction with phosphate in detergents with calcium in hard water
ooh reduction in washability? What did that mean in practice?
Commercial washing of sheets is done with low liquor ratio (to save costs). This affects rinsing quality which retains HA, so the problem builds up over time
Were the sheets washed in industrial detergent that contained more phosphate than domestic laundry products
Low liqor ratio? Can you explain?
Was it proved the phosphate source was detergent or assumed? If proven then how was this done?
Reduction in washability for the sheets manifested itself as poor stain release and poor crease recovery – both of which came about by HA build up preventing effective water absorption in commercial laundering
I think low licquor ratio means that there is less water/detergent mix in the drum relative to the weight laundry. Is that right?
@iona. Yes, the problem was exacerbated by industrial detergents which contain high levels of phosphate
@kate. Quite right
@Ian, how much HA was in these sheets, w/w?
Lower liquor ratios save water heating costs, but the commercial laundries don’t realise that cost saving comes with a performance deterioration
So is low licqor a bit like under dosing detegent
@Ian sorry we are deluging you with questions now!
@sophia. For the sheets the HA build up was in the region of 10%
OK, so the hydroxylapatite on the fibres means that they can’t absorb the liquid so well, and washing out stains relies on getting the fabric wet.
I like jessica’s question above
@kate. Absolutely. Crease recovery also depends on wetting out the fabric effectively
I was wondering that too, Iona. I think the lady in the group who used to run a nappy laundry said you can use much lower doses of detergent because of the way they wash, but would that even out as equivalent to underdosing in your washing machine…
…or is it an appropriate dose for a more efficient process?
I like Jessica’s question too.
@iona. I don’t suppose the phosphate was ‘proved’ to come from detergent – unfortunately we rarely deal in ‘proofs’, more suppositions and hypotheses based on test results and research. However in that case the detergent was equivalent and multiple laundr
Jessica’s question – was it proven that phosphate was from detergent or assumed? If proven, how was this done?
Also we could not isolate another source of phosphate in conjunction with the sheets, because obviously urine wasn’t a factor in that case
Ian, would that suggest that there was more than enough phosphate available in that case, so getting the mix for hydroxylapatite to form would rely on the availability of calcium, hence harder water showing more problems?
As an aside are the graphs from the infra red spectrum interesting to look at? Would it be possible to send them to sophia, so she could share with group?
Kate – yes the presence of phosphate was the latent building block for HA. However this required the calcium from hard water to ‘spark’ the reaction. If the laundry had only been in a soft water area no HA would have built up
Thanks – just thinking ahead to how we can identify phosphate source! Do we know the phosphate content of the detergent solution? Thinking we could compare that to urine phosphate.
Iona – the graphs (spectra) are interesting to look at, if you know how to interpret them! It is quite a skill! I can certainly forward examples to Sophia
We did a bit of calculating and I think the opposite is likely true for nappies. eg. rather than industrial detergent which is 40% ish phosphate…
Domestic would be something like less than 0.5% and we thought that there would be more calcium than phosphate available.
Ian could you clarify if the low liquor means less water and detergent or lower water (so higher detergent concentration)? Relates to whether they are underdosed as asked above.
Jessica – the phosphate content of detergent in the nappy washes would depend on teh detergent used by the householders. Also phosphate content of urine varies wildly dependent on the performance of the kidneys
What about in the cotton sheets? Do you know what form the phosphate in the industrial detergent was?
Jessica – low liquor ration means ratio of liquid to product, not ratio of detergent to liquid
Thanks Ian
so its about cost of heating water, rather than anything about detergent per se
Kate – I’d have to check the form of phosphate in industrial detergents. I can’t remember the specific example, it was a couple of years ago. I’m not sure it was even quantified at the time, the info was taken from the MSDS of the detergent
Detergent conc could be higher due to less water
Iona – yes its all about cost of heating water, the kettle is one of the households most costly devices
I have a suspicion that industrial laundries can dose someingredients separately while domestic detergent goes in as a set mix. So perhaps you could use less detergetnt without the same domestic underdosing problems of not softening the water.
Iona – the detergent concentration is calculated on the mass of product in the wash, not the amount of water. Water is essentially just a transport medium. However lower liquor ratios give absorbency issues, the less water present the harder it is to absorb.
Brilliant info. Because we know that in the domestic setting your dose is calculated by the water, to make sure the stabiliser is sufficient.
Kate – absolutely. In my experience most commercial laundries operate very odd procedures, we have dealt with several large projects discussing their efficiency
do you have ideas about removing ha aside from 90  degree washes – would vinegar help?
Unfortunately with commercial laundries their performance is driven by cost and throughput, not the quality of the washed items. I have personal experience of a laundry that allows and accepts a 10% loss of product every year, because it is cheaper to wash fast and poorly than to try to recover affected items
The test detergents we used in phase one were standardised ones called ECE. The phosphate version they make uses hexametaphosphate. We read how that is actually good at breaking down hydroxyapatite. I wonder if that’s the widespread…
Iona – the solubility of HA is poor, and even a 90 degree wash didn’t effect full removal. Strong acids might help so I would give vinegar a try, just don’t expect a miracle cure. Far stronger acids would have more of an effect but then they would affect the base material, and even dissolve it
Because if so it might mean that with the sheets the poor wetting was the real danger, rather than the phosphate content.
@Ian, have you found HA on any other laundry?
Kate – the phosphate was teh cause of the HA build up because it is the phosphate that reacts. But you are quite right that poor wetting has affected the reaction, due to ineffective removal of the phosphate into the drains thus leaving it on the sheets
If we’re pretty sure HA worsens absorbancy would it seem reasonable to use absorbancy (eg wet/dry weight) as a cost effective proxy for HA quantity? Thinking as our experiments are limited by time and cost it could be a way of assessing HA accumulation or removal on a nappy.
Ooh that’s a really interesting idea, Jessica.
Obviously not hugely accurate and would need to account for other confounders but might be an idea
Sophia – not as part of an investigation but only because it has not been a focal point of the enquiry. I
Ian, what I mean is, why wasn’t everything in hard water areas full of hydroxyapatite when we used phosphate detergents? If that hexametaphosphate was the widespread choice it may have been helping prevent it when liquid was sufficient.
Jessica – very valid point, and I appreciate that HA tests by ashing are expensive. If you had two separate nappies which both weighed xg dry and when wet one weighed 2xg and the other weighted 5xg it is a reasonable hypothesis that something is preventing water absorption on the first one. All else being equal, this may well be HA
Thanks Ian
Do you have a notion of how much a certain amount of HA deposit would affect absorption?
There are other confounders that would need to be considered but this might be a good way to isolate only certain nappies for full HA tests by ashing
Kate – not really know, this is more of an experience thing based on performance of product in the field. Certainly 10% had a profound effect on sheets but towels might need a higher % as they have a non-uniform surface? I’m afraid there probably isn’t a numerical answer.
I was also thinking that if we tried to create HA then it could be a good preliminary test. Ie test absorbancy of piece of nappy/prefold before urine/detergent/hard water and test again afterwards.
Thanks, Ian. That sounds quite an appreciable amount anyway so it’s worth considering.
That’s another great idea, Jessica.
Ian, can I check, does HA also make it difficult for the cloth to dry once it has been wetted?
Thanks Kate! Enjoying using my brain again while on mat leave 🙂
@Ian – the sheets with the 10% HA, do you know roughly how many times they’d been washed to get to that stage?
Jessica -m that is a possible scenarion that I’ve mentioned to Sophia. However you would have to allow HA build up over a significant period of time. I suggested dipping a piece of nappy material (or a whole nappy) in phosphate loaded water and allowing it to dry naturally every day for a month. You’d have to do teh same with artificial urine solution.
If we saw big differences, it might be a way people could get an idea at home, eh?
Sophia – 100+ times easily, some had been washed 250+ times
True Kate could lend itself to an experiment at home
Kate – this sort of thing is a very good idea to try at home. Do teh same dipping experiment in various places in the UK (to get a range of calcium contents from different hard water levels)
It’s hard to guess how often nappies get washed but we worked with 100 times a year as a rough idea in the first phase.
Alternatively create a set hardness of water and use it as a standard solution
@Ian – and does the nappy need to dry in between? It forms as it dries, is that right? It can’t form in solution?
It is easy to create water of a certain hardness simply by adding calcium salts to tap water. I can calculate values and forward to Sophia if you like?
Thanks, Ian. Yes please. That might give us an easy way to test the hypothesis that hard water makes HA formation more likely.
Sophia – yes you really need to dry the nappy in between. Otherwise the liquid from dip 2 washes off a large proportion of the forming HA from dip 1 and so on
Sophia – as previously, can I suggest that you collate all action points from this discussion and forward to me as a work item? I’ll follow this up with information to yourself and you can share it with the group
Sophia, but it can form in our kidneys as kidney stones? Is that what we heard in the recent chat? But I understand what Ian is saying about growing them that way.
Kate – correct, in the case of kidney stones the phosphate source is urine not detergent
@Ian, sure, I can do that.
Ian, that’s made me think. Does that mean that, even with a phosphate detergent and hard water, in normal washing conditions you would still expect to remove some HA from a nappy which was still wet after use?
And, might it suggest that ‘wet pailing’, where you put dirty nappies in a bucket of liquid until the wash, could help if urine was providing the ingredients for HA before it even makes it to the wash?
Kate – HA build up is a slow process, only a very small amount will ‘grow’ with every wash – most phosphate will flush away with the rinse water. Consider it as a stalagtite growing slowly over time due to calcium build up on its downward facing point
Kate – if you ‘wet pail’ you are keeping the phosphate in liquid so making it easier to flush away before HA build up starts
I feel like we should wrap up quite soon, and let Ian get back to his work. What do we want to ask him before he goes?
@Ian – you said you have seen HA on other laundry, but it has not been a focus of investigation. Can you say what kind of quantities of HA would you ‘expect’ to see? Is our 20%ish on some of the nappies unusually high?
Are we still open?
@Kate, I think we are but it has gone quiet…
20% on nappies is certainly high – as was 10% on laundered sheets. However it should be noted that both these products are of a type that are necessarily washed some hundreds of times
You would probably never notice HA build up on apparel because you wpould never wash an item of clothing so many times that its absorbency would become an issue
The one last thing I wanted to ask is a bit off topic and it was just if Ian could (whenever convenient) expand a bit for us on what he said about detergent build up in the last chat. when have you observed it, exactly what ingredient builds up?
Or its crease recovery
what was the effect with bio enzymes and how did that work?
And also limescale. We see sources stating that limsecale can build up in fabric? Have you observed that?
Kate – no problem at all. Can I suggest that you frame the question(s) to Sophia to be included in my follow-up work order? I can then provide fuller information
Brilliant, thank you!
Kate – limescale is a similar issue just with a slightly different chemical reaction. It is still build up of insoluble calcium deposits exacerbated by hard water conditions
@Ian – Final rinses in a washing machine – would they make HA (or limescale) buildup more likely or less likely?
(I mean, some people do extra rinses after their nappy wash to make sure all traces of detergent are gone or whatever.)
Sophia – the better a rinse is performed, a higher number of rinses or rinsing with excess water will all serve to reduce HA build up because they all serve to rinse away the phosphate from the detergent
The sample needs to be spun in the machine also to remove as much loose water as possible prior to drying, less residual water = less possibility of HA build up
@Ian and is that true of limescale too? (Not that we found any evidence of limescale buildup in the nappies you tested for us)
Extra rinses to remove detergent are often done to reduce possibility of skin irritation – some of the surfactant and bleaching compounds in detergents are known skin irritants
Its tru of any potential insoluble calcium deposit
Great, thank you.
Thank you A4D gang for coming. Ian, thank you so much for giving up your time to answer our many questions. It’s been fantastic to have your expertise here!

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