What is in ironing aids and how do they work?
Ironing aids (such as Fabulon) have four components:
1. Water. This provides a steam cushion as the hot iron glides over it.
2. Gliding agent. This is typically a silicon oil that is colourless and odourless and provides a lubrication for the iron as it glides across the fabric
4. Starch (either natural or synthetic). Starch of course is the component that stiffens the fabric when it is ironed. But it’s not the actual starch that stiffens the clothes. If you just sprayed some starch on your clothes and let it dry, it wouldn’t make a scrap of difference to the stiffness of the fabric.
What is needed to stiffen the fabric is starch plus heat. This produces a process called hydrolysis which is essentially where the starch molecule is broken into bits and water is added across the bonds at which the molecule is severed.
These bits of starch are simply short chain carbohydrates and they are termed dextrins. Dextrins have a number of properties in the food and pharmaceutical industries, and one of them is the stiffening of clothes. This occurs as the dextrin binds to the fabric (particularly cotton) and helps straight and out the physical structure of the weave.
Interestingly, dextrins are also the stiffening agents in the crust of a nice crispy bread.