Dixie -- I use the powder with cold water. As long as the soap is powdered finely enough, it dissolves quickly and the mix works fine. The only way I know of to powder soap finely enough is to use a food processor with a blade and to break the soap into powder at the right moment when it's firm enough to handle but waxy enough to break down easily. If you don't have a food processor or wait too long to process the soap, the soap bits stay too coarse and the soap won't fully dissolve, especially in cold water. In that case, you may need to use warm water for washing or pre-dissolve the powder before use.
Other caveats to keep in mind for others who might be reading this -- Use a very high % of coconut oil or pure coconut oil to make the soap so it is fast dissolving. Grate and powder the soap just as soon as the soap has firmed up enough to grate and powder. If you wait too long, the soap will be too hard and too dry to powder well. I use gloves to handle soap this young, because the soap can still have some excess lye at this point and is irritating to the skin.
PandP -- I think homemade laundry mix does a good job as long as I keep some things in mind.
1. Deal with hard water. The laundry mix recipe we've been talking about is based on soap, not synthetic detergent, so it won't do a good job in hard water. Soap scum that forms when using soap in hard water will turn your white clothes grayish. You either need to add a separate water softener product (Calgon makes one) to the wash water or use a home water softener. Adding a chelator (sodium citrate or tetrasodium EDTA) to your soap recipe will also be very helpful. I don't view a chelator as a substitute for softening the water, but it sure helps.
2. Use enough of the mix to actually clean. Many recipes out there in the internet blogger land say to add ridiculously small amounts of the laundry mix to the wash load. For clothes that only need a freshening, that might work okay, but for truly dirty clothes, this is just plain not going to work. You will need to experiment with how much to use to get the results you want. With my laundry mix (1 part soap, 1 part washing soda, 1 part oxyclean clone), we get good results with 2-3 Tablespoons per typical load, maybe another TBL for a really dirty load.
3. Use the right water temperature. Commercial laundry detergents (Tide) work well in cold water. Homemade laundry soap mix often works pretty good in cold water, but for especially dirty loads, soap is even more effective if you use warm water.
4. Pretreat stains. Commercial laundry detergents include enzymes to break down blood, grass stains, etc. and homemade mix doesn't include these ingredients. If you want to efficiently remove stains like these or heavy greasy stains, you will want to pretreat stains with a homemade stain stick or a commercial pretreat product (Shout).
I do not cure my laundry soap mix -- once it's ready to use, we use it. Curing helps bath soaps to be as mild as possible to the skin, be as long lasting as possible, and develop a lather quickly and easily with a wash cloth or against the skin. Laundry soap has a simpler job -- it needs to dissolve fast in a large-ish amount of water and it needs to clean clothes -- kind of a different situation.
