You send the linen out and it comes back with pieces set aside, with a surcharge you did not expect, or with an awkward phone call: "we can't process this". It looks arbitrary, and it is not. An industrial laundry works to written criteria — and the good news is that you can read them before signing anything: the technical specifications of public laundry tenders, for hospitals, care homes and publicly owned hotels, set out exactly what is accepted, what is rejected and who pays when something is damaged. This guide is built from four of those documents and from the Spanish Ministry of Health's hospital linen manual.
Composition decides the process, not taste
This is the point that most surprises anyone who buys textiles thinking only about handfeel. The specification from the Huelva provincial purchasing authority says it flatly: the service "requires a guarantee of thermal disinfection at high temperature for items that are 100% cotton, and for the rest through chlorine products in the case of polyester, always at medium temperature".
Translated: pure cotton is disinfected with heat, and a polyester blend cannot go up to that temperature, so it is disinfected chemically at medium heat. Two different routes inside the same plant. For the thermal guarantee the same document applies the Demière scale: "10 to 14 minutes at 90-95 degrees, or 16 to 24 minutes at 85 degrees". And it adds a detail that explains a lot of shrinkage: linen "must not undergo sudden changes of temperature (greater than plus or minus 20 ºC)", with the heating and cooling ramps watched closely.
The practical consequence is simple: if you buy 50/50 sheets and 100% cotton towels, you have not bought "white linen", you have bought two processes. When it all goes into the same bag, someone has to separate it — and if they do not, some piece travels the wrong route.
Chlorine is the invoice you do not see
INGESA's hospital linen manual describes the mechanism with a clarity no catalogue offers: when the areas of fabric that have absorbed chlorine meet the temperature of the bath, "chemical attack on the cotton fibre occurs, and the typical tears appear". On ordinary bleach it warns that, having no stabilisers and being difficult to dose, it "can cause holes and various tears".
Its recommendation is hydrogen peroxide, "one of the noblest disinfectants known", for 15 minutes at 80-90 °C. This is not a matter of preference: it is the difference between a sheet that leaves circulation worn out and one that leaves it holed halfway through its life. When you ask for a quote, ask which bleaching system they use and at what temperature. Almost nobody asks, and the answer tells you a great deal about the plant.
No mark, no claim
In a plant processing several clients' linen, identification is not bureaucracy: it is the condition for your linen coming back to you. The specification for Área VIII in Murcia requires "installation of a chip or electronic device in every item… guaranteeing control of deliveries, returns and traceability, of the RFID-UHF type", and writes down the other side of it: items "lacking the electronic counting and control device" may be "rejected by the contractor, who will therefore not take charge of cleaning them".
There is one answer to "why did they send these pieces back unwashed". The Huelva document describes the same problem from the other end: when a garment arrives unidentified, "it would be impossible to know which member of staff it belongs to".
If you are a small property sharing a plant, the affordable version of this is a heat-sealed or sewn label carrying your identifier on every piece, and a count sheet per delivery. Without one of the two, you lose any argument about missing pieces.
Ironing has a width, and a temperature
Industrial ironers are built to specific widths. Girbau publishes a working width of 3,000 to 3,500 mm for its PC range: the line is designed for large flat pieces that fit that width. On what happens inside, the INGESA manual specifies the contact: linen must go into the calender "at 160-180 degrees C, as a minimum, for 15-20 seconds, and be folded immediately… and must come out thoroughly dry".
Put that beside the ironing limits of the international textile care code, GINETEX: hot iron, "maximal sole plate temperature of 200 °C", corresponding to the cotton/linen setting; moderate, "maximal sole plate temperature of 150 °C", for wool, silk, polyester and viscose; and low, "maximal sole plate temperature of 110 °C", for polyester, polyamide and acetate. A calender at 160-180 °C sits above the ironing limit of a good many synthetic fibres.
Do not conclude from this that "blends cannot be ironed": the finish depends on the specific fabric and its data sheet. What you should do is ask which of your pieces go through the calender and which are dried and folded, because price, finish and what the guest sees all depend on it.
What you can take as given is which pieces never reach the flatwork line. A fitted sheet with an elasticated hem, a duvet cover with a flap, or anything carrying elastic, a zip or buttons is not calendered: the line is built for flat rectangles that go in one end and come out folded at the other. Those pieces are dried and folded, by hand or by machine, and are usually billed separately. Non-standard sizes carry a penalty for the same reason: they force the feeding station to be reset and slow the whole line down.
Moisture on delivery: a criterion you can demand
Tender specifications do not only impose duties on the client. The Huelva document sets a quality threshold anyone can copy into their contract: clean linen "must be delivered with a maximum moisture content of 2%; if delivered above the stated percentage it must be processed again". The specification for the Sierra Nevada resort, which is a hotel contract, repeats the same figure: linen is delivered "free of moisture (2% maximum permitted)".
If your linen arrives warm and damp and is put away like that, the smell problem that turns up three days later is not the fabric's fault.
What gets set aside, and why you should ask for it in writing
A good plant does not retire pieces silently. Huelva formalises it: clean linen "not fit for use will be delivered separately, stating the cause: deterioration, tearing, irreversible stains, etc.". That is a retirement report, and it is exactly what you need in order to know how much you replace a year and why.
In the other direction, the Murcia specification sets the standard you can demand on every delivery: each piece "must be in perfect condition of cleanliness and pressing, without stains, tears or wear, in perfect condition as to colour, seams and fastenings", and those that fail "may be rejected". The same document forbids mixing clients: "in the washing process, batches of linen of different origins or natures must not be mixed".
To that list, practice adds a separation the tender documents do not spell out but any plant observes: terry and flat linen are not washed together. Towelling sheds lint that clings to sheets and pillowcases, and it asks for a different programme and a different drying cycle. If you hand everything over in one bag, someone will have to separate it before loading; if they do not, your sheets come back covered in lint.
Who pays when something is damaged
Here is the clause worth having in any contract, and it appears in these documents as a matter of course. Sierra Nevada: "in the event of loss or damage attributable to the contractor, it must replace the items with others of similar characteristics". Huelva imposes the same: the contractor is obliged "to replace items damaged for reasons attributable to it".
The other half of the conversation is the client's responsibility. The Huelva document classes as an incident linen returned damaged "because of some object in a pocket of the garment such as a pen, a scalpel, etc.". In a hotel the equivalent list is familiar: pens, hairpins, room keys and chargers travelling inside a duvet cover. Checking before bagging is free.
Two standards you will be quoted, and what they actually say
When you ask for guarantees, standard numbers will appear. It is worth knowing what they cover:
- ISO 15797, Textiles — Industrial washing and finishing procedures for testing of workwear. Its scope says it "specifies test procedures and equipment which can be used in the evaluation of workwear… intended to be industrially laundered", and adds a sentence almost nobody quotes: "this document does not provide instructions and specifications for the procedures and equipment to be used by industrial launderers". It is a laboratory standard, not your laundry's manual.
- ISO 6330, Textiles — Domestic washing and drying procedures for textile testing. It "specifies domestic washing and drying procedures for textile testing". Domestic: if a data sheet says "tested to ISO 6330", it is telling you how the fabric behaved in a laboratory domestic wash, not how it survives an industrial tunnel.
- EN 14065, the RABC biocontamination-control system for laundered textiles. It is the certificate most plants display, and it is worth reading for what it says: it attests that the laundry runs a management system for microbiological risk, not a particular wash recipe and not a sterile result. It is a good sign about how the plant is organised; it does not replace asking about temperatures, chemicals and processes.
Neither is a supplier lying; they simply do not answer the question you are asking. The useful question is a different one: how much dimensional stability the piece keeps after repeated industrial washing, and how fast its colour is to chlorine.
The list for your next conversation with the laundry
- Which route does each composition follow: thermal disinfection or chemical at medium temperature?
- Which bleaching system do you use, and at what temperature?
- How is my linen identified, and what happens to an unidentified piece?
- Which pieces go through the calender and which are folded without ironing?
- What is the maximum moisture content on delivery of clean linen?
- Do you deliver unfit pieces separately, with the cause stated?
- Is my linen mixed with other clients' in the same cycle?
- Who replaces a piece lost or damaged by the process, and how is it valued?
With those eight answers in writing you will know more about your laundry than most hotels on your street, and you will be able to buy textiles that fit its process instead of fighting it every week. If you are also deciding whether to buy the linen or rent it, the comparison between renting and buying changes with these answers; and for when a piece stops coming back into circulation, the renewal guide gathers the signs.