Most people who put clothes in a charity bag or a collection bin assume they'll be worn by somebody locally. A share are. The rest enter a global trade in used textiles that's much larger and much less visible than the donation model implies.
The sorting stage
Donated clothing gets sorted, usually by commercial operators rather than by the charity itself, into grades.
The best material — good condition, current styles, recognisable brands — goes to domestic resale, in shops or increasingly online where margins are better.
The next grade is exported. There's a substantial international market in used clothing, with major exporting countries in Europe and North America and major importing markets across Africa, Asia and Eastern Europe.
Lower grades go to industrial uses — wiping cloths, insulation, shoddy fibre for mattress filling and similar. This is genuine recycling, of a sort, though it's downcycling rather than making new clothing.
What can't be used at all goes to landfill or incineration.
The export question
The international trade is where the ethics get genuinely complicated, and reasonable people disagree.
The case in favour: it provides affordable clothing in markets where new clothing is expensive, supports substantial local employment in sorting, repair and retail, and keeps enormous quantities of textile out of landfill in the exporting country.
The case against: the volume and declining quality of exported clothing has grown to a point where receiving markets cannot absorb it. A meaningful proportion arrives unsellable and becomes a waste disposal problem in countries with less waste infrastructure. There have been well-documented accumulations in several importing countries.
There's also a long-running argument that cheap imported used clothing undermines domestic textile manufacturing in receiving countries, and several have restricted or attempted to restrict imports for that reason.
My honest read is that the trade was broadly beneficial when volumes were lower and quality was higher, and that the growth of very cheap clothing has shifted the balance considerably.
Why quality matters so much
The critical variable, and it's changed within a generation.
A garment made from durable fibre with decent construction has multiple lives — resale, then another owner, then perhaps repair, then eventually material recovery.
A garment made from thin synthetic fabric with glued seams has approximately one life. It cannot be resold in decent condition because it doesn't survive being worn, and it can't be usefully recycled because blended synthetics are extremely difficult to separate.
So the growth in volume has been accompanied by a fall in the proportion that has any onward value, and the two effects compound.
The recycling problem
Textile-to-textile recycling — turning old clothes into new fibre — is where the hope tends to be placed, and the technology is genuinely difficult.
Mechanical recycling shreds fabric back to fibre, which shortens the fibres and reduces quality, so recycled content is typically blended with virgin material and the loop isn't closed.
Chemical recycling can break polymers back down to feedstock, and works best on single-fibre materials. The problem is that most clothing is blended — cotton and polyester together, with elastane, plus dyes, coatings and trims — and separating those is the unsolved part.
Progress is real and the scale is currently tiny relative to production volumes. Anyone claiming this is solved is selling something.
What actually reduces the problem
The uncomfortable answer is buying less and keeping things longer, which no commercial interest has any reason to promote.
The environmental footprint of a garment is dominated by production. Extending the life of a garment reduces its per-wear impact roughly proportionally, and that's the largest available lever by some distance.
Practical versions: buying fewer, better-made items. Learning basic repair — a replaced button or a mended seam extends life substantially and takes ten minutes. Washing less aggressively, at lower temperatures, and line drying, all of which reduce wear as well as energy use.
And buying second hand, which has become dramatically easier and now covers essentially every category.
Making donations more useful
If you are donating, a few things genuinely improve the outcome.
Only donate things you'd give to a friend. Damaged or worn-out items cost the receiving organisation money to sort and dispose of, which comes out of their funds.
Wash things first. Unwashed donations are frequently discarded.
Use textile recycling points for genuinely worn-out items rather than putting them in a charity bag. They're usually accepted specifically for material recovery, which is where they should go.
And where a charity runs its own shops, donating directly rather than through a commercial collection bin means more of the value stays with the cause. Not all collection points are what they appear, and some are purely commercial operations using charitable-looking branding.
The resale market caveat
Second-hand buying has grown enormously and it is genuinely better than buying new. One caution worth adding, because the effect is documented: for some shoppers, cheap second-hand availability has increased total consumption rather than displacing new purchases.
If someone buys ten second-hand items where they would previously have bought three new ones, the environmental benefit is smaller than it looks, and the volume of clothing eventually needing disposal is larger.
That is not an argument against buying used. It is an argument for the same discipline either way. The lever is total volume and length of ownership, and a wardrobe acquired cheaply is not automatically a wardrobe kept longer.