I’ve been reading in some of my sericulture books, about using a hydrochloric acid bath to break the diapause, and make the silkworm eggs hatch *this* year instead of next year. Well, I tried the acid wash last night.
I felt like about half frightened high-school lab student, half mad-scientist. For some reason, I can make up sodium hydroxide (lye, for my soapmaking) in big pitchers and not give it a second thought, but a beaker of hissing acid freaks me out. Maybe it’s just because it’s the first time. If this goes as hoped, I’ll be doing it relatively often.
I dusted off my old, tired math skills, and figured out that the standard, 20’Baume, 31.45% acid (sold as Muriatic Acid at my local hardware store), needs to be approximately 2/3 by weight in solution, with the remaining 1/3 being water, to get the right “weight” of acid, which has a specific gravity of 1.10.
I found out something important – kraft paper cannot be replaced by card stock. The book says to have the moths lay out on starch-covered kraft paper, so that when you dip the paper into water, the starch will allow the eggs to separate and become free from the paper. What happened instead, is that the cardstock became pulpy, and I ended up with little rafts of eggs clinging to bits of pulp. I think the next batch will be on freezer paper; I’ve had much better luck with that.
The first thing I did, was get the eggs off the paper, and then soak them in a salt bath (specific gravity between 1.06 and 1.10) to see which ones would float and which would sink. Floaters (after the pulp raft issue was sorted out) were removed, since they are often infertile. Sinkers were rinsed in a coffee filter-lined sieve using clean water, and then introduced into the hydrochloric acid bath. They soaked there for seventy-five minutes, because the book says 60 to 90 minutes, and I figured I’d take a middle path to start with. I didn’t get the impression that there was a functional reason for the time range. On the tables for using the hot acid treatment, there are much more limited times.
I sieved out the eggs (again, with a coffee filter) and then rinsed thoroughly and repeatedly with clean distilled water. I set the eggs on the coffee filter in the soap room to dry, and then put them into containers in the morning. Now, I just have to wait and see if they’ll hatch! I’m excited.
Hydrochloric acid (HCl) neutralizes with baking soda, making, if I remember my high school chemistry correctly, water and salt with some carbon dioxide on the side. Dilute with water, and then neutralize it before you pour it down the drain, being careful not to let it fizz over and make a mess. If you have excess baking soda in the sink from rinsing stuff down, then any drip of the acid will hiss like mad, and it feels like you’re in a cartoon watching the acid eat through the table.
Yes, I wore gloves (nitrile), a particulate mask (the good kind, not the dinky kind), and goggles. I also wiped down surfaces after with a baking soda’d sponge.
HCl will mark stainless steel, that is to say, my sink. Glass and certain plastics are OK; I used a tempered glass canning jar. I stirred with a plastic disposable spoon, which didn’t seem to suffer damage.
Acid into water, never water into acid. Acid heats up when it dilutes (thanks, Jenny!), and it can boil over if it gets too hot. I did the dilution in a bowl filled with ice water, just in case.
Hydrochloric acid is sold in hardware stores, as a tile and plaster cleaner. I got a hydrometer to measure specific gravity at a wine-maker’s supply store for $5.99.