The Acid Bath

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.

28 replies
  1. admin
    admin says:

    Thanks! I’m very hopeful – this would be a significant advancement for some of the things I want to do. I’ll post in about a week and a half, whether it works or not.

  2. admin
    admin says:

    A “lab prep” question – any idea how vigorous the dilute acid is? It’s 21% HCl after I get done mixing it down. I mean, clearly it will mark the stainless sink, but if I get some on my arm, is it going to eat a hole in me as I watch? Or is it more of a sunburn type thing? I know that with the lye, a small splash will burn me over the course of a few minutes, but I don’t have to run screaming for the shower, I can afford to finish stirring and pouring, and THEN wash up.

  3. admin
    admin says:

    Like I said, I think I’m going to try freezer paper. The plastic lining helps it work well for what I need. I think that Kraft paper is probably just all they have available in India.

  4. shadowduchess
    shadowduchess says:

    Oh, alright I mean if it meant ripping you off half a yard or yard of it (this is the designer brown kraft paper we’re talking about right?) then I could have done that for you as we have a massive roll of it here for pattern making and I could prestarch it as well.

  5. blaisepascal
    blaisepascal says:

    What’s the idea?

    You said it would make the eggs hatch “this year” instead of “next year”. However, elsewhere I thought you said that all that was necessary to winter over the eggs was to store them in a cold environment (refrigerator) for a month. Does this shorten that time? Or is this something else? Or do I misunderstand something?

  6. admin
    admin says:

    Re: What’s the idea?

    This totally removes the requirement for cold storage.

    The eggs naturally want a cycle of long cold. They will hatch after a month or so in the refrigerator; this cuts that waiting time out entirely. They should hatch ten days from now, if all goes as planned.

    When I’m trying to breed for color, it will allow me to have one generation after another with no long break; that means I’ll be able to make four or five specified selections in a year, instead of just one or two. It also allows me to work with eggs that haven’t sat in the refrigerator for a long time; they dry out a lot in storage. Hatching percentage of fresh eggs is usually twice as good as old ones, or more.

    I’ve learned (the hard way) that the eggs from an early April rearing are not nearly as vigorous the following April, as the eggs from an October rearing; I’m getting better at managing their storage and keeping them in good shape.

  7. admin
    admin says:

    Ironically, mine either. The mathematical part (which a lot of the Chemistry stuff is) is what kept me from pursuing a degree in Biology. But, if I can figure it out ONCE, then mentally transfer it from “Chemistry” to “Cooking” – I’m fine. Formulae frustrate me, but recipes aren’t a problem.

  8. unluckymonkey
    unluckymonkey says:

    Now I’d like to see pic of that! Tubes and masks and rubber gloves oh MY!

    I was just going to find your journal and post qith a question about inkle weaving. I made a swank inkle loom this past week and have tested it out. I didn’t mess up and it does work but now I need to learn pick-up techniques. I figured out how to do the float to make surface design but I can’t find any good online explanations of pick up. Does one literally draw up the warp thread of choice that’s currently down and pull it up with the treads you’ve drawn up or am I completely cracked? Our library sucks for weaving books so I’ve been scouring the net for good pick up techniques and though if ANY one could give me a couple pick-up lines it’d be you! 😉

    I hope your Eggsperimant works! It sounds like madness to soak eggs in acid to get them to hatch sooner. Then again I’D wanna jump out of an egg soaked in acid sooner than expected too.

  9. emmasee100
    emmasee100 says:

    Hello, I’m a professional lab chemist and your proceedure looks fine to me.

    I hate acids (which is a bit of a problem in my line of work) and itch after I have to work with them. Even with personal protective clothing.

    It looks like you’re staying safe which is important. Good luck with your eggs.

  10. admin
    admin says:

    That’s the thing… I don’t know if it’s the designer roll type, or more like paper bag, or what. They don’t specify, which I assume means they’ve got some standard kind there.

    I found out the sad, upsetting way, that a lot of our US papers aren’t good for caterpillars. I’m gussing they either have something in the process, or they’re treated to keep off bugs. The food-safe stuff, like wax paper and freezer paper, seems to usually be safe.

  11. admin
    admin says:


    It went smoother than I had worried it might; once I got the mix right, it was just like anything else that gets a wash and a soak…

  12. admin
    admin says:

    There are several different techniques for inkle pickup. The one that I used the most, which creates the most delicate and controllable surface pattern, is called basketweave pickup. You warp 2 background threads and then 1 pattern thread; this sets up a background weave which shows up as dots. You make the pattern by pushing down the pattern thread where you want the background to be empty. I made graph paper for it on the computer; it’s on a diagonal like peyote beading paper (which also works). I haven’t done the kind that starts out with a striped warp.

    I have some patterns around here somewhere, but it’s been a looooong time since I did any of it.

  13. unluckymonkey
    unluckymonkey says:

    Ahh I see. I’m going to dig through your journal now for pics of your lovely and inspiring weaving. Are you a floor/table loom owner? For some reason I always assumed you were using an inkle loom for your fabulous bands as thye were inkle loom sized.

    Thanks dear!

  14. admin
    admin says:

    Oops. Hit the ‘send’ button too fast.

    I do most of my stuff using tablets; I use an inkle loom as a framework, but the shedding isn’t done with heddles. I’ve done a lot of inkle work, but it’s been a while.

  15. shadowduchess
    shadowduchess says:

    Ahhh okay, I understand!

    Eeeep, not cool it sounds like a processing chemical that they inject into it. Hopefully it works with the freezer paper, keep us posted!

  16. unluckymonkey
    unluckymonkey says:

    naughty monkey! I looked at one of your weaving posts to read the perplexing words Tablet Weaving. I am now looking into how to use my inkle loom for tablet weaving. 🙂 I’m thinking of fixing my loom downstairs and then I’ll have a 40″ floor loom a table loom converted to a 8 harness floor loom and my trusty little inkle loom. Something about weaving has got me in its grips! I refuse to become one of those ladies with 6 looms full of unfinished projects though. that = naughty.

  17. unluckymonkey
    unluckymonkey says:

    yeah that’s what I wanna do! I’ve found some info on tablet weaving but I’m going to have to either find a better page or a book at our crumby library. Do you have any favorite links for using tablets to plan/make designs like your smashing lettering?

  18. admin
    admin says:

    Check out – lots of good band weaving info there!

    Linda Hendrickson has some great pattern books, and good info on graphing – one of her books, Please Weave a Message, features one of my alphabets.

    If you’re wanting to design your own, I can give you a lot of hints and tips. You can use Excel to make a graph (which is really a chart, with shaded bars) or I use a program called PatternMaker, which has a lot more Windows-based graphical interface functionality.

  19. unluckymonkey
    unluckymonkey says:

    OH thank you so much for the link and info! Yeah I plan on designing my own. I’m a fussy artist that way. So I might be knocking on your door for assistance if something’s not doing what it should. 🙂 Thank you thank you thank you. It can be SO hard to find people to chat with about weaving.

  20. admin
    admin says:

    My best hint: do some sampling, find out what YOUR graph looks like, and design around that. The biggest problem that people have, is that their designs come out stretched because they designed it on a grid that doesn’t fit their weaving. For doubleface, my grid is 3:1; for brocade, 1.5:1. YMMV.

  21. unluckymonkey
    unluckymonkey says:

    Thanks dear. Yeah I was thinking about that when looking at others patterns. I do ahve one small question. Do you know any tricks to keeping your edges clean? Right now I’m playing with the inkle loom jsut making a simple patterned strap and despite my best efforts to keep the tension on the edges consistent it’s pretty crummy looking. I know if I used a thicker weft it would correct a lot of that but for finer work like my sample it’s jsut a little too messy looking for me. 🙁

  22. admin
    admin says:

    I’d have to see it, to be able to exactly diagnose.

    Three suggestions: you may find that one or more of these will work for you personally.

    First, I use a pin, hooked in the two first fingers of one hand (the “going from” side) to straighten the weft. Pull against the pin, and the weft will go straight across, and you can delicately seat it against the edge of the warp.

    Second, I sometimes will pinch the edge of the warp, and gently tug the weft against it when drawing through. That helps hide the weft.

    Third, when you beat and draw through, leave a small picot at the edge. Then, change sheds and beat again, and tug the picot closed before making the next pass.

    If your problems are more of a wavy edge, you may just need practice. Because there is no reed, the inkle system relies more on draw tension and less on the machine.

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