Recycling Film

 On the Recycling of Transparent Film

    The thin, crackly film on the top of some food packages which might be clear (as on top of a punnet of grapes), or opaque (as on a pot of cream), is often carefully labelled "do not recycle". What material is it? And what is the problem about recycling it at home? 

    There are many types of 'plastic' involved in food packaging but it is dominated by four main types of material: PE = poly-ethylene, which comes in several high and low densities; PET = poly-ethylene-terephthalate; PP = poly-propylene; PVDC = poly-(vinyl-dichloride). There is considerable confusion on the 'web' as to what is used where, for the exact chemical determination is beyond the reach of most of us. I have tried to unravel the conflicting views. Thus [1] thinks the crackly, rustle-ly, film that 'lids' a grape punnet is PP, while [2] thinks it is PET. Reference [2] thinks PET stands for poly-ester while [3] thinks PET stands for poly-ethylene-terephthalate. Sainsbury's thinks that the 'lidding' film cannot be recycled with the plastic punnet and the plastic milk bottles, but OPRL [3] thinks it can go in the blue bin with glass, tin, aluminium and other plastic. Webprofab [4], comparing  PP with PET, says PP is translucent while PET is as clear as glass. Cling film (Saran Wrap in the USA) was originally a polymer of -( CH2 - CCl2)- called vinylidene chloride, though vinyl di-chloride would seem more logical. (Wikipedia is confusing about Saran Wrap and cling film; it is not made of PVC.)

    The PlasticPractical website [1] compares two materials, and suggests: 

"To tell polypropylene (PP) from polyethylene (PE), start by noting their texture and firmness. PP is stiffer and less flexible, while PE is softer and more pliable. Conduct a burn test; PP produces a blue flame with a sweet smell, whereas PE gives a yellow flame with a waxy odor. PP will sink in water due to its density, while PE often floats. Look for recycling symbols: PP has a #5, while PE features #1 or #2." [1]

 

    According to [2] there are three material to consider.

"Polypropylene (PP): The "Display King." Known for its crystal-clear transparency and high gloss. It is stiff, has excellent moisture resistance, and is widely used for snack wrappers and clear over-wraps where visual appeal is paramount.

"Polyethylene (PE): The "Workhorse." Available in Low-Density (LDPE) and High-Density (HDPE) variants. It is soft, stretchable, and has superior impact resistance. It is the go-to material for shopping bags, shrink wraps, and heavy-duty industrial sacks.

"Polyester (PET): The "Barrier Shield." PET offers high tensile strength and thermal stability. It provides excellent barriers against oxygen and scents, making it ideal for food packaging that requires a long shelf life or high-temperature resistance (like lidding films).

   

(Wikipedia clarifies. Poly-(ethylene-terephthalate) (PET), where the polymerising unit is -(C₁₀H₈O₄)- , is a poly-ester, but only one of many. It is the same material a terylene™  and dacron™ . )

    Some of the issue are [A] melting temperature, [B] permeability to (a) oxygen, (b) water, or (c) food odours, [C], transparency, [D] flexibility. I think it is the first three issuse that affect the choice for lidding films, as they often show off the product and are glued in place using Hot Melt Pressure-Sensitive Adhesives (HMPSA). Some packaging tells us not to recycle the lidding film; some tells not to recycle it as home, but take it with PE "bags to a large supermarket". I think both are now out of date, as I found a seminar put on by Bostik [5] that offers to: 

• Illustrate how resealable films containing Hot Melt Pressure-Sensitive Adhesives (HMPSA) are fully recycling compatible with existing polyolefin recycling streams and comply with recyclability guidelines of thermoformed PET trays.
• Show that resealable films based on two distinct HMPSA technologies are rated similarly with regards to recycling in existing/future streams.

Conclusion  

    I have not learned what prevents lidding film from being recycled domestically. The materials used are very varied and are often multilayered. There is a confusing plethora of advice on this issue, coming not from the government but from the food and packaging industry, trying to be good ecologists. But I have concluded that with present-day (2026) technology, there is no longer a need to separate the lidding film from the tub or tray.   

References

[1] https://plasticpractical.com/plastic-identification-how-to-tell-polypropylene-from-polyethylene/

[2] https://www.newtopmachine.com/blog/industry-insights/pp-pe-pet-film-packaging-guide/

[3] https://oprl.org.uk/simpler-recycling/

[4] https://www.weprofab.com/pp-vs-pet/

[5] https://packagingeurope.com/rethink-resealable-lidding-film-recyclability/9621.article

Prime Minister 2

    I want to continue my theme of 29th April [1] titled 'Prime Minister'; so I have titled this post 'Prime Minister 2'. Twelve days ago Sir Keir Starmer was being badgered by the media over his handling of the Epstein/Mandelson affair; now it is the aftermath of the revolutionary, but inconclusive, election that is exciting the media (radio, TV, press). 

    On of my issues is a side swipe at the media; and in my case that means the BBC radio. It seems to me that, in an attempt to whip up interest, they over step the mark and instead of reporting on the news they become part of the news.

    Another issue was the loss of the idea of corporate responsibility. Why, I wonder, would it help the country if Wes Streeting replaced Keir Starmer? They should both be deep in the same quagmire; both putting their shoulders to the wheel to get the vehicle moving. 

    No one doubts that there is a great deal of frustration in the country about the way things are going. My own list of grumbles might include: our failure to curb Russia, USA, Israel, unemployment of school- and college-leavers, a rising benefits-budget, continued illegal immigration (albeit at a slower rate), collapsing health (and dental) services, cost of housing, cost of living, potholes. Sure! There is much that appears to be going wrong.

    But the idea that either Reform or the dispirited Conservative party could do better seems to me ludicrous. Admittedly, there is not much that the average citizen can do other than to cast a vote. As some of our comedians have said: the votes cast for Reform and the Greens are really anti-votes, against Conservative and Labour.

    There is a faint trace of rationality in the idea of lowering taxes in the hope of 'kick-starting the economy'. Equally rational, however, is to raise taxes to invest in infrastructure. We dither. We try both. We clearly need more than that level of leadership.

    I wish there were a coffee-house somewhere in London where one could go to see and eavesdrop on real grown-up experts talking about politics. Or go to Frankfurt, Paris, Milan; or Stockholm, Oslo and Copenhagen. I mean –– how are our continental colleagues coping with their own economies?

    Perhaps that 'coffee-house' is Twitter, or Bluesky.

Hanta Virus

 Hanta Virus

    Hanta Virus came to me as a new disease, a new problem, a new phenomenon when I heard (on Sunday 3rd May 2026) of the outbreak on the Dutch cruise ship MV Hondius. It appear that the first death on board occurred on 11th April in mid Atlantic 11 days after leaving Argentina. The body was evacuated to St. Helena on 24th April and repatriated to Holland with the wife of the dead man; by today (5th May) the wife had also died. 

    But Hanta Virus is not all that new. Several people knew already that the Hollywood actor Gene Hackman and his wife probably both died of the virus in February 2025 [2]. And the US Department of Health has been tracking known cases of the pulmonary form of the disease (Hantavirus pulmonary syndrome, HPS) since 1993 when there was a cluster of cases in the 'Four-Corners' area of the United States (Arizona, Colorado, New Mexico, and Utah). In the 30 years between 1993, when monitoring in the States began, and 2023, there were 890 cases of hantavirus disease reported. The fatality rate was the alarming 35% [3]. 

    But the Hanta Virus family of viruses seems to be a great deal older than that. They have been known to science since 1978 [4], and seem to have co-evolved with their rodent hosts over a period of many millions of years [5]. While showing considerable specificity for their host rodent, be it the deer mouse in the the mid-west United States, which carries a virus that focuses on the lungs, or the bank vole and the common rat both of which carry viruses that attack the kidney (causing Hemorrhagic Fever with Renal Syndrome, HFRS), we see from the outbreak on the cruise ship MV Hondius that the virus can occasionally jump host, to another rodent, or to humans [5].

    Structurally the Hanta Virus family are small spheres with a single membrane coat covered in glycoprotein spikes through which the virion attaches to a target protein in host cell membranes, usually integrins, but not always. 

    The genome comprises three small pieces of single stranded RNA in negative orientation [6]. (In COVID the single-stranded RNA is in positive orientation.)

(Added 7th May 2026)

    The three pieces of ssRNA that constitute the genome as called large, medium and small or L, M, S.

Large, containing 6.8 – 12 kilobases (kb), codes for the RNA-dependent RNA polymerase. A recent paper in Nature [7] describes its structure in considerable detail and proposes a possible mode of action. 

Medium, containing between 3.6 and 3.7 kb, codes for the two glycoproteins, Gc and Gn, which, as hetero-dimers, form the coat, the spikes and the docking mechanism.

Small, 1.7 - 2.1 kb, when copied, produces a positive stranded messenger RNA that codes for the Nucleocapsid protein whose role is to coat the single negative strands of these three genomic segments [6].

    The symptomless 'incubation' period seems to be longish and variable; 1-2 week but exceptionally up to 8 weeks. This may be a feature of negative-single-stranded RNA viruses, and the complex process of activating the polymerase described by Durieux Trouilleton et al. [7]. 

I shall add to this article as I acquire more information. 

References:

[1] Guardian: Ashifa Kassam and agencies, Tue 5 May 2026 02.52 BST

[2] Ewan Somerville, BBC News, Published, 15 April 2025

[3] https://www.cdc.gov/hantavirus/about/index.html

[4] Edward C Holmes, Yong-Zhen Zhang, "The evolution and emergence of hantaviruses" https://doi.org/10.1016/j.coviro.2014.12.007

[5] CDC – https://www.cdc.gov/hantavirus/about/index.html

[6] Hanta Virus – An Overview. March 23, 2022 by Sagar Aryal, PhD. https://microbenotes.com/hanta-virus/

[7] Durieux Trouilleton, Q., Barata-García, S., Arragain, B. et al. "Structures of active Hantaan virus polymerase uncover the mechanisms of Hantaviridae genome replication". Nat Commun 14, 2954 (2023). https://doi.org/10.1038/s41467-023-38555-w

(Comments are welcome to Cawstein@gmail.com)

Prime Minister

UK Prime Minister: An impossible job

I write this on 29th April 2026, at the end of two weeks of stressful chatter in our news media. The UK parliament was asked if it wanted to accuse the Prime Minister of 'lying to parliament'; a fatal accusation if they decided to make it? In the end they did not. I felt that we heard too much of this unfortunate kerfuffle; surely (I believed) there was more important news! 

It has been borne in on me, over the last few months, that the job of being Prime Minister in the UK has become well-nigh impossible. It is a case of job-inflation, which started (perhaps) with Margaret Thatcher, and was pushed forward by Tony Blair. Our prime minister was traditionally regarded as Primus inter pares (first among equals), not as the solitary decision-maker, which he has become. I think we do not want a President, a chief executive. Our prime minister should be merely the convenor and chairperson of the Cabinet. 

I do not think the BBC helped. Indeed, I think the BBC exacerbated the problem. Their interviewers puggled away, and worried the ministers; they stoked the blaze. (I expect some newspapers were as bad, but my only exposure to 'the media' has been the BBC, our quasi-independent-dependent broadcasting company!) I think the 'U-turn'-jeering could even be said to have caused errors, such as Sir Keir Starmer's peremptory sacking of Sir Oliver Robbins ('Ollie' Robbins to the media).

I do not think Keir Starmer should have sacked Oliver Robbins, though I understand his momentary anger. I understand that there were two errors involved: I doubt Keir Starmer was aware that Sir Oliver was, himself, not privy to the text of the vetting; but the latter could have explained, if not the content of the vetting, at least the process. 

In any case, I do not think Keir Starmer can have sacked Oliver Robbins, for I do not think he could sack him. I believe that Keir Starmer did not employ the civil servant; so it was not in his power to un-employ him. (See my point above, about job-inflation.) Many other people have made mistakes on the route to here. 

I think Sir Oliver Robbins should be re-instated. 

Grammar: accusative case

  Grammar: Trouble with the Accusative Case.

  I am enjoying learning more about Miss Mary Bennet, the unfortunate third daughter of Mr. Bennet esquire of Longbourn in the county of Hertfordshire; unfortunate in inheriting neither her mother's beauty, nor her father's intelligence. We learn of her adventures in London after the death of her father, in a 'spin-off' novel by Janice Hadlow,  called "The Other Bennet Sister"; and a BBC drama series of the same name written by Sarah Quintrell.

Her misfortunes are compounded by a lamentable grasp of English grammar, in particular she fails, as does her older sister Jane, in the use of the Accusative Case. She ends the second 'Chapter' by remarking: "Father had found a way out, leaving Mother and I (sic) with nothing, except each other."  And yes, as I said, Jane is blighted with the same solecism. At the opening of the third chapter, Jane says "Mary, you must come and stay with Mr. Bingley and I (sic). ". The problem may go deeper, even involving Sarah Quintrell, Lindsay Salt and staff at the BBC (British Broadcasting Corporation).

Poor Mary! At the first occurrence I winced. At the second, I leapt out of my chair, determined to do what I could to save all present and subsequent generations of young people from stumbling their way through this mine-field. 

Britain has clearly decided not to bother teaching grammar, so it does not help much if I refer to concepts like Nominative and Accusative Cases. (These concepts are so much clearer in Latin. The nominative case is used for subject nouns, the accusative case for object nouns. "The ball (nominative) hit the centre stump (accusative). In modern English there are only tiny trace of these distinctions. "I (nom.) speak"; "He spoke to me (acc.)."  But, that sort of instruction is lost on the modern youngsters. ) 

I have a much simpler way of teaching the correct usage; temporarily leave out your companion (Mrs. Bennet or Mr. Bingley in my examples). So, for Mary:
"Father had found a way out, leaving Mother and I (wrong ) with nothing, except each other.", becomes:
"Father had found a way out, leaving ... me with nothing, except ....".  So, after restoring the companion:
"Father had found a way out, leaving Mother and me (right) with nothing, except each other.",
(No one would dream of saying "....leaving I with nothing...." . It is the companion that interferes and misleads.) 

Similarly, for Jane:
"Mary, you must come and stay with Mr. Bingley and I (wrong). " becomes:
"Mary, you must come and stay with ........me  ". and eventually: 
"Mary, you must come and stay with Mr. Bingley and me (right). "
(No one would ever be tempted to say "Mary, you must come and stay with I" . It is the companion that misleads.) 

It is clear that the above error of 'Me-avoidance' comes from a fear of committing  the opposite, and even more common error of 'Me-insistence'; "Me and my friends did it". This error is of a completely different sort. Mary Bennet's error of 'Me-avoidance' is committed by people who are trying to be correct, and think they are succeeding; the 'Me-insisters' know they are wrong, but 'insist'  for that reason. It is a teenage thing and is spontaneously abandoned  when the perpetrators leave school. However, it is, once again, the companions that cloud the issue, while assonance encourages the error. 

Tax and Spend 2

 Tax and Spend version 2

  

   Back in July 2016, I wrote a piece on this blog titled "Tax and Spend" [1]. I remarked at the surprising fact that neither the 'Deficit Spending' school of macroeconomists (Keynes, Klugman, Chick & Pettifor, etc.), nor the 'Austerity' school (Hayek, Friedman, etc.) seemed to be able to convince the other school. Each could see the power of their own argument but not that of the other school. The issue was left in the hands of the politicians,  who were ill equipped to understood either argument.    I could understand parts of each school, but hoped there was a simpler way of revealing the logic. I tried to build a simplified model of the national economy; crude but robust. It illuminated very clearly the so-called 'multiplier' whereby money injected into the system goes round and round, doing more good, to more people, than you might at first expect. I ended, not as a 'Deficit Spender' but a 'Tax and Spender'. 

     I have gone over the argument again, improving and correcting. Let me show you. 

     Imagine a country that neither imports nor exports, neither goods nor services. Suppose that, in a certain fiscal year, the aggregated income (AI) of its citizens is 1 trillion pounds sterling (AI=1,000B£). Imagine that every citizen pays income tax (IT) at a flat rate (ITR) of 20p in the pound on all income (ITR=0.2), saves (S) 18% of net income (S=0.18), and spends the remainder. 

     (To estimate the fraction saved I shall consider incomes of greater that £200,000 p.a. to be saved and not spent. Clearly these super-rich will spend a little; but, equally clearly, some of the merely-rich will save a little. HMRC figures for 2022/3 suggest that total national income was 1347 B£, while that earned by the super-rich (so saved in this model) was 244 B£. So 18.11% of the total. For convenience I count as saved 18% of net income.)

     (I note that approximately 1/3 of UK government revenue comes from VAT and that governments use VAT as a fine-grained  way of directing our spending patterns. (Thus, food is exempt, but ice-cream and crisps are VATed). I shall initially assume that 1/4 of the purchases are VAT-free, and that VAT is charged on 3/4 of the  purchases at a rate of 20% (VATR=0.2).)

     Both the VAT-free and the VATable 'spend' is spent in this notional country, so it forms the gross takings of some of the citizens. If spent on bread, part will buy flour and fuel for the baker, but part will constitute income for the baker. Suppose (initially) that, for every business (or for businesses in aggregate), half the gross taking is spent on raw material (RMr=0.5) and half constitute wages (W). (I.e. Wages/net income = Wr = 1-RMr).   

     Looking now at the income of the government we can see that it is the sum of the income-tax takings (ITT) , and the VAT takings (VATT). What will the government do with the Total Tax (TT)? It will spend a fraction on wages (FW), a fraction on benefits (FB), a fraction on infrastructure (FI) and will waste a fraction (FW). Let us, rather arbitrarily, set these as follows: FW=0.5; FB =0.33; FI=0.1; FW=0.07. Note, however, that benefits constitute the income of a fraction of the population. Also that infrastructure includes roads, schools, libraries, the army, etc., while a fraction of tax inevitably produces no benefit, and is essentially wasted. (I am told that 'Benefits' comprise  roughly 10% of GDP, while wages comprise c. 75% of the cost of  the NHS.)

     All these quantities (see Table 1) enter the model as constants but are initial values only, and the simulation can be re-run with different values. 

The Results Table (Table 2) is like a 'Bagatelle Board'. We put 1 T£ in at the top left. Some is spent by the citizenry and some is routed to the Treasury. At the end of 'round one' a sizeable fraction (c. 60%) of both tax money and private spending emerges as more income, so that part goes round again. And that again produces more income, repeatedly until the sums get too small to bother with. The final GDP is the sum of those repeats.    

     What we want to know is the final result, in terms of final GDP (fGDP), final saving (fS), final tax (fTT), final infrastructure (fI), final private spend (fPS), and final Waste (fW). (See Table 3.)

Conclusions

(1) The multiplier effect is striking; varying from 2  to 2.5. Seeding with a GDP of 1 trillion and ending with 2.0 – 2.5 trillion.

(2) A surprising result is that GDP increases 10% when taxes are raised from 20p to 30p in the pound. Presumably because government spending recycles more than private spending.

(3)  Infrastructure benefits by a striking 58% when taxes are raised from 20p to 30p in the pound. The government has 58% more money for roads, schools, army etc. 

(4)  The downside of raising taxes from 20p to 30p in the pound, is that the money for private spending is reduced, but only by some 13%. It need not fall at all for the poorer half of the population, if the tax system is suitably 'progressive'. Tax rises are difficult to sell to the public, but perhaps not impossible, if we clearly need, and want: better army, better roads, better schools, NHS, etc. 

References:

[1] https://occidentis.blogspot.com/2016/07/tax-and-spend.html 

=============================

Nature Notes

 Village Nature Notes

On my afternoon walk the other day, in the last week of March, I passed an old rabbit warren. The path is easy to follow at this season, for there are no nettles yet, and the numerous rabbit holes on either side of the path are clearly visible. As I approached one hole, with the sun over my shoulder I could see right into the hole, and there, barely a foot from the opening, was a half-grown baby rabbit, enjoying the sun. He would be safe enough from the many dogs that will pass that way. And ferrets are rare.

Seeing several brimstone butterflies and (today) a small tortoiseshell, reminded me that I had not seen 'Barry' for 6 months. For ten years, I used to see him regularly getting on or off the bus from town. His ashen pallor, his dejected carriage and expressionless face always giving me the impression of a person more dead than alive. Poor Barry. He believed he was doomed to die from a chronic disease of the lungs; yet he got about, and never seemed short of breath. He was agreeably slim and carried his weight easily. In fact, apart from his pallor and fatigue, he looked quite fit; until you saw his eyes, and felt the full impact of his apparent despair. 

For five years Barry never noticed me, never wasted a glance in my direction. Nor did I ever see him speak a word to anyone else. Then, one day, on the bus coming out of town, I saw Barry in animated conversation with a couple I did not recognise. I felt rebuked. It was clear that he could talk to people he knew, or people who interested him. I managed to catch his eye when we both got off the bus. Within a week we were on speaking terms, and soon after that we exchanged christian names. He told me that the small tortoiseshell butterfly was, this year, very rare in our corner of Northamptonshire. I mentioned that I had seen several brimstones. He told me the names of all the butterflies he had seen already that year; and he had seen a lot. He was fond of Bruckner, a composer I admitted I had not been drawn to, and there I let Barry down. But he told me the lengths and opus numbers of all his favourite Bruckner symphonies. 

With that wonderful memory for detail, I wondered what his job had been, eager to 'place' him relative to my own limited world; for he was not quite an academic, nor was he a professional. It turned out, and I would never have guessed, that he had made his living by buying and selling British porcelain. Again I was quickly out of my depth; I only knew two facts about early British porcelain, gleaned from living for five years among the china-clay pits of central Cornwall, so my part in the conversation was soon exhausted. But Barry was able to name, date, and place all the famous eighteenth century makers of British porcelain from Cookworthy to Spode, from Chelsea to Bristol to Worcester to Staffordshire. He could probably have told me every piece he had ever bought, or sold. We met frequently on the bus, would sit together and list butterflies to each other, or discuss the dates of the romantic composers; topics on which we were more evenly matched.  I went abroad at the end of September, and though I returned at Christmas I have not seen Barry since. 

I was standing in my dining room, recently, looking out over my small garden, enjoying the consciousness of having nothing pressing to do. I love my resident song birds; the blackbird that sings at dusk, the robin that sings whenever I go out into the garden. And I would include the wren and the dunnock who flit about in the ivy. Then a flash of speckled brown wings. A large  bird swooped over the hedge at its lowest point, crossed the lawn and disappeared. A glimpse, lasting less than a second. Too brief to identify a sparrow hawk, but I fear that is what it was, and that he might have snatched one of my cherished residents.

My voice, manner, or dress has a curious effect on some people. Yesterday, shortly after five pm, waiting at the retail park for the bus to town, a cheerful and chatty man came towards me across the road towing a wheelie shopper crammed full of polythene bags. Were those purchases, I wondered, or his worldly possessions?

"You have been shopping!" I offered. 

"Oh, that is our laundry," he replied. "Our washing machine is giving trouble". He grinned, revealing a complete absence of upper incisors. I could not think how he came to be with his laundry in the retail park for there was no laundromat there.  Apparently, his wife was shopping. 

He told me that he was a gardener – a conversational jump which I think he must have introduced, for I am inclined to stick to topic when conversing. Once we were onto gardening we stuck to it and chatted for half an hour. Was I a gardener? 

"Keen," I said, "but not gifted, for weeds and pests overwhelm my efforts. "

"Dandelions" he said. 

"Taraxacum officinale" I responded. 

"Thats right" he agreed, delightedly. "So you know the Latin!"

He lived at Byfield; had been head-gardener at Wardington Manor for 15 yearsl lovely garden. I was starting to tell him that I knew Lord Wardington, then corrected myself. One evening,  standing in the middle of the road, I had chatted awhile with farmer Brakespear about Lord and Lady Wardington. 

"Oh, I knew John Breakspear very well, lived in upper Wardington, opposite The Plough." 

And so we rattled on. The late bus arrived though his wife did not. "There is another bus in half an hour."  So we both got on, and continued our reminiscences. The bus dawdled down Middleton road in heavy traffic, till I had to jump off, desperate for a pee. 

        A good conversationalist, John Gardner. (He may have told me his name, and where he trained, but I have forgotten, so I have called him John, provisionally.)