Why does some fabric develop creases when washed that are impervious to washing out and that cannot be ironed out, and other fabrics get permanent folds that are equally resistant to ‘flattening’?
The edging on a sheet - cotton
!Trim on a dress - knit
The same happens on sleeves, collars, and so on.
It’s all to do with the molecular structure of the fabric. The answer to your question of why and how to stop it is here: How chemistry can make your ironing easier.
If I want to remove these sort of creases, I put the iron on as hot as the fabric will tolerate, and turn the steam up. If the fabric is more sensitive, use a damp cloth to protect the fabric you are ironing.
I read one suggestion that if you spray on diluted vinegar (1 part vinegar to 3 of water) prior to ironing, the wrinkles are removed.
Been there, tried that, didn’t work. It flattens the crease but the crease ‘mark’ remains. Each time the target items are washed they crease (fold) the same way.
Next time the iron is out (could be a while now) I’ll try that.
Ta, 
has not been answered. Especially why the sheet edges always folder over (two times, not just once!) when washed.
Ironing sheets, a rather rare and peculiar pastime, but fear not you can conquer those wrinkles! Success will come but at the price of smelling like a cheap salad bar in a heat wave. To get best results be sure you use organic vinegar that would be most important and align your ironing board with your qi too.
We used boiled starch, a good soaking, ring out till damp, and then steam press. No wrinkle could defy that. Of course every error was permanent until the next wash. Apparently works best on khaki coloured cloth linen table cloths. Could never understand the logic of using it on table napkins.
Creases add character to fabric 
Removing them is character building!
I’ve tried to treat it as some kind of defining experience of mental focus and self control, a challenge for body and mind to come together in perfect harmony to overcome the seemingly impossible. The problem is, for me it never seems to have the ‘seemingly’ part, and it usually descends into a much less spiritual growth experience where I just grow angry and frustrated and end up using the fabric as-is, creases and all, and ponder the bad things I could do to the inventors of fabric, irons, ironing boards and people who expect me to display perfect fabric flatness. Just responding to this post makes me feel slightly agitated 
As ‘The Sandman’ said - ‘failure requires no preparation’. With creases, I don’t even set out to fail, I simply don’t set out. I do have an iron somewhere … refer iron maintenance topic
@PhilT you have my sympathy. I remember similar crusades many many moons ago. I think you need to accept that some fabrics are possessed by evil spirits, or something like that …
The answer for both is that the fabric was incorrectly tensioned in manufacture and then was cut without the fault being apparent. What this just means is that an error occurred when the fabric was made and cut and even thought it looks ok at the factory when it is washed and the mill’s added fabric stiffeners etc are washed out the fabric relaxes and shrinks (most are not preshrunk before making items) and you see the crease formed. It is a permanent feature but may be able to be somewhat fixed by unpicking the hemming and restitching but you may end up with uneven cloth. In the sleeves and similar where it is not part of the hemming it is a permanent fault and is not repairable and you can only disguise it by adding like others suggested a stiffening agent which will be removed by washing or soaking in water.
I like the theory, but the sheet is not a crease, it is a perfect fold along the edging whereby the edging literally folds over itself, twice, along each entire length, no twisting to be seen.
Most of our sheets (3 sets) are much heavier than the norm cotton and every one of them has done and continues to do this. We can press the folds out and the next wash back they come. We have one set of regular weight ‘easy care’ sheets that does not do it.
Re the clothing, the wash induced folds are almost perfectly ‘half high’ of the fabric whether the dress decor in my photo, or the edging on a sleeve, and are not those that develop from fabric cuts that promote non-uniform tension / shrinkage; I can readily identify those and understand what happens and why.
So far, s/still wondering
Some of that is due not only to the cut but the tension used in manufacture. The fold or even multiple folds occur due to both the cut and the manufacture of the fabric and become apparent only after washing. Both add to the problem. Sometimes the bias is cut incorrectly and this can also cause a fold after washing and natural shrinkage, I asked our old tailoress what caused it and those were her answers.
My mother who was a clothing designer (and later a seamstress) would say the fabric has been ‘cut on the bias’ i.e. not perfectly aligned with the warp and the weft. It is why sometimes trouser creases are not well aligned. A design and manufacturing fault.
There seems lots of that in clothing these days, and I am aware at what that looks like in practice.
However, these are not those.
Thanks for The Sandman reference! Straight to the book of quotes!
Perhaps the less obvious but absolutely trivial solution is to never wash the items at all!
Put the laundry detergent in the same cupboard as the iron. Very good for the environment, saves water and reduces carbon emissions.
We had lunch out today and the palace of fancy food had topped the crisp table top with a thick glossy sheet of white paper trimmed to the able top. No laundry, no stains to wash out, no new creases to lament.
I think a bias cut means you can cut diagonally across rather than with the weave. It is tricky and finishing the edges is a bastard I imagine, but it means a standard tabby weave fabric (prior to recent technology) can actually stretch and adapt to the body. Many early twentieth century actresses made great use of the the bias cut!
Hi all.
Whenever the bed sheets are washed, the edges curl, making for an untidy look. This never happened to sheets bought over 20 years. Still using the same machine and washing methods, but the edges all curl on the newer sheets, some brands more than others. The only difference for me is that I moved from Darwin to Adelaide.
Have other members had similiar problems and did they overcome them?
Thanks
Just a guess, it’s the humidity or lack thereof.
To be honest we’ve never noticed. Aside from the folded down edge of the top sheet, the edges all disappear under the mattress when made.
Is there are a particular brand, style, material this problem is related too?
P.S.
We mostly wash in warm (tepid water) and line dry.
Ah, yes I remember the bias-cut dresses that are in my wardrobe somewhere. I loved them, but could never quite pull off the slinky silk ones that were seen around that time.
