There are a couple of different ways to make your own laundry starch, though the most successful methods require that you start with a refined starch of some variety first — usually either corn or potato-derived. Both corn and potato starches are widely available in most markets, usually as a powder. In most cases all you’ll need to do is add water in measured doses to turn these into a helpful liquid laundry products. Potatoes are so starchy naturally that, for the purposes of a laundry solution, you can sometimes boil the tuber whole to get a liquid that will work with some degree of success. The resulting solutions uses are limited to laundering and clothes stiffening purposes, though. Actually making raw starch as would be needed for cooking is significantly more challenging, and often requires a lot of time and specialized equipment.
Laundry Starch Basics
Starch is a multi-purpose laundry tool that can help keep wrinkles at bay as well as prevent dirt and sweat stains on collars. Most of the time it’s sold as a spray, often in an aerosol can. A number of manufacturers include one or more chemicals along with the starch, and might also incorporate fragrances or other additives to help laundry look and feel fresh. If you aren’t interested in these additives or don’t want to pay the often high retail price for this product, it might make sense to try to make starch at home. The ingredients will cost far less than a can of aerosol starch spray, won’t include added preservatives that can damage clothes, and are completely biodegradable. All you’ll need to get started is a powdered base and some room-temperature tap water, plus some way to measure both and a basin or bottle for the finished product.
Cornstarch Base
There are a number of different ways to make starch for clothing, and experimenting may be the best way to discover which method gives you the crispest collar or otherwise gets you the results you’re looking for. Using everyday cornstarch is often the simplest method. Cornstarch is made from natural corn kernels, and is sold in most grocery stores and markets as a thickening agent — cooks often keep a box of it in their kitchens to add substance to broths, soups, and even baked goods. For laundry purposes, you'll need 1 heaping tablespoon (about 15 grams) of cornstarch and half a quart (1 pint or 473 mL) of cold water.
Add the cornstarch to the cold water and stir until it is completely dissolved. The solution will be cloudy, but there shouldn't be any clumps visible. You’ll want to be sure to use the solution sparingly to avoid a dusty residue as the garment dries, and most people have the best luck with a spray bottle equipped with a “fine-spray” setting. Always shake the bottle before spraying. A cornstarch-based spray will generally give you a stiff finish; if you prefer an even stiffer finish, try adding one additional teaspoon (about 5 grams) of cornstarch at a time until you get the result you want.
Potato Alternatives
If you prefer a softer finish, you might want to try using a potato base. Potato starch is often available in commercially, usually near flours and other baking products in the store, and you can follow the same proportional directions as with cornstarch. If you have a bit more patience, though, you can also start with a raw potato.
You will need one potato, boiling water, a heat-resistant bowl, and a spray bottle. Wash the potato and peel it thoroughly. Place it in the bowl and cover it with boiling water, then let it sit overnight to release as many of the natural starches as possible. Strain the liquid to remove any solids and pour it into the spray bottle. This starch is perishable, so you will want to use it within 48 to 72 hours. After that point, it could begin to grow mold or harbor other bacteria. You’ll also want to use it sparingly, since what you’re basically doing is spraying boiled potato on your clothes; if you use too much you could end up with a residue or smell that will require re-laundering the clothes.
Tips and Tricks
It’s usually a good idea to make sure that you let any home-made solution sit on your clothes for about a minute before ironing to prevent any white marks from forming. Using the finest mist available is usually the best way to start, as it’s always easier to add more than it is to take away excess. If your iron has a “steam” setting, try using that before using full heat.
Homemade starches might need to be more heavily diluted if you’re going to be soaking the clothes rather than spraying them. People who are air-drying their clothes typically spray the solution on damp garments as they are hung or they may also dip the entire thing in a diluted starch solution, usually in a bowl. Starching a collar for a shirt might be easiest with a quick spray, for instance, but soaking might be best if the goal is a crisp pair of underwear. If you’re using an electric dryer, you’ll probably want to spray the starch on when the clothes are almost dry, then use a hot iron to seal it in. The result should be crisp and neat, though this can take a bit of practice.