What silk does in soap
Soap makers add silk, usually in the form of tussah silk fibers or a product called liquid silk, in the hope of a smoother, silkier feel and a creamier lather. Some also report a slightly firmer bar. These benefits are widely repeated among makers but are largely anecdotal, so view them as possible rather than guaranteed.
Tussah silk fibers vs. liquid silk
- Tussah silk fibers are raw strands that you dissolve in your lye solution. They are inexpensive and a small amount goes a long way.
- Liquid silk is a hydrolyzed, water-soluble silk product. It can be stirred into your liquids without waiting for fibers to dissolve, which many find more convenient.
How to add silk fibers
- Measure your water and put on gloves and eye protection. Lye is caustic, so work in a ventilated space and follow a trusted safety guide.
- Cut or tear the fibers into very small pieces, right over your lye water container if you like, so there is more surface area.
- Add the lye to the water (never the reverse) and stir. The heat and alkalinity break the protein fibers down, typically over around 20-30 minutes.
- If small bits remain after the solution cools, strain it through a fine stainless steel mesh into your oils.
How to add liquid silk
Follow the supplier’s directions. Many makers stir it into the cooled lye solution or other liquids in the recipe. Because suppliers differ in concentration, use the rate on the label.
How much to use
Makers commonly describe using a small pinch of fibers, on the order of a cotton ball or around a gram or two, per pound of oils. Treat this as a rough guide; more is not necessarily better, and too much may leave a stringy texture.
Troubleshooting
- Fibers will not dissolve: Cut them smaller, give them more time, or strain.
- Odor: Dissolving protein in lye can produce a noticeable smell, which usually fades.
- Color: Dissolved silk may slightly tint the lye solution.
Are the benefits proven?
There is little formal testing that shows silk changes soap in measurable ways, so the evidence is mostly maker experience. The oils you choose usually matter more for lather, hardness and gentleness. Our guide to oils used for soap making is a good place to start, and superfat influences skin feel too.
Frequently asked questions
What is liquid silk made of? It is generally a hydrolyzed silk protein solution, derived from silk and made water soluble. Check the supplier’s ingredient list for specifics.
Is Dawn dish soap safe to use on silk? This is a fabric-care question, not a soap-making one. Silk is delicate and generally washed with a gentle, silk-appropriate detergent; check the garment’s care label.
What happens if you add too much lye to soap? The bar can become lye heavy, which is harsh and may irritate skin. Use a lye calculator and an accurate scale, and keep a small superfat as a buffer.
How do I make handmade soap? Beginners should follow a tested cold process recipe from a trusted source, with proper protective gear. Our artisan soap overview shows what makers do beyond the basics.