Wednesday, December 29, 2010

Natural Dyes - Scouring

The Maiwa Guide to Natural Dyes
What they are and how to use them


Proper scouring is absolutely essential to good dyeing. Improperly scoured items do not dye evenly, the dye does not penetrate well, and the dyed item may not be fast.

Most fibres come from nature with coatings of some type. If these are not removed the dye will attach to the coating rather than to the fibre. This may not be immediately evident but over time the adjunct will separate from the fibre taking the colout with it. It is a common error to doubt the fastness or the quality of the dye when the real culprit is a freeloader who stole the dyestuff. It is best to remove all foreign matter at the beginning and start with clean fibres.

Note: Fabrics sold as “ready for dyeing” may not need scouring.

Supplies: 

Soda ash and Neutral Soap (Synthrapol) for cotton.
Orvus paste soap (for silk and wool)

Scouring cotton and other cellulose fibres:

1  Use a large vessel and fill with enough water so that the yarn or fabric may be well covered and not crowded.

2 Add 1 tsp Synthrapol (5 ml) and 4 tsps. soda ash (20 g) for each half-pound (250 g) of cotton.

3 Simmer for approximately 1 hour. Cotton is full of wax, pectic substances, and oil, all of which must be removed. The resulting wash water will be yellow brown. Bleached white cotton yarns and fabrics may not need as long.

Scouring silk and wool:

1  Use a large vessel and fill with enough water so that the yarn or fabric may be well covered and not crowded.

2 Add 1 tsp (5 ml) orvus paste soap for each pound (500 g) of dry fibre/fabric.

3 Add yarn, fleece or piece goods and heat gently (60º C, 140º F) for approximately 1 hour. Turn gently but do not agitate

4 Allow fibre to cool down slowly and then rinse in warm water. Remember overheating or sudden temperature changes will cause wool to felt.

Notes:


  • Some fleece sold as scoured has also been oiled to facilitate spinning - it will need to be scoured again.
  • Fleece and wools need to be scoured to remove natural oils (lanolin) and dirt.
  • Silks require scouring to remove sericin - the coating of the fibre that held it into a cocoon.
  • Cotton and other plant fibers require scouring to remove waxes and pectins.
  • In all cases anything that comes between the dye and the fibre will create an unwanted resist.

Comparison of unscoured cloth (left) and scoured cloth (right).
One piece of fabric was torn in half - everything other than scouring was the same.








The Maiwa Guide to Natural Dyes



20 comments:

  1. Thanks Maiwa. It's so easy to skip steps like these to save time. Thanks for reminding me of the importance of it; I'm a better dyer for it.

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  2. The 1 tsp (5 ml) orvus paste soap used for silk and wool is per pound of dry fabric/fibre. (We left that out of the original post)

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    Replies
    1. Is there an alternative to orvus paste soap? I can't find it in the UK

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  3. Is it necessary to scour wool roving that doesn't say 'ready to dye'? It looks so immaculate and clean already.

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  4. Elizabeth: The short answer is yes - clean fibres will always dye better and have a stronger bond with the dyestuff. Having said that, roving is perhaps the most forgiving as unevenness will be less noticeable after the spinning process. If your roving seems very clean already you can probably spend less time scouring it than you would normally.

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  5. I will be attempting to dye jute. I actually bought burlap shrub wrap at a garden shop and then took the weave apart so I would just have jute "yarn". I will be using several natural colors of dye (greens, browns, some yellows). Does jute need this scouring process? Also, will your natural dyes work well with jute? Thanks in advance, and nice website.

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  6. Jute needs to be scoured just as any fibre, possibly even more. Scouring removes both natural impurities and manufacturers treatments and allows mordants and dyes to properly penetrate and bond with the fibres.

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  7. Because soda ash is imported in the country I live it is very expensive and not always available. Are there common household safe biodegradable alternatives I could use to scour cotton? Salt, washing up liquid?

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  8. In the recent MAIWA in Bengal Masterclass posts, it was mentioned, "Before the day is over we review enzymatic scouring. In our post on scouring (linked here) we encourage it, and Michel introduces wheat bran as a natural enzymatic method. As a quick test we tear a cloth in two; scour one half but not the other, and then place both in an indigo vat. The results are a little startling."

    Can you tell us what is meant by enzymatic scouring, and how can it be done? The effectiveness shown by the sample of scoured to unscoured is obvious. Is it more effective than our usual methods used here? What are some advantages to enzymatic scouring?

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  9. Is synthrapol toxic? I had heard that it was (possibly in a workshop I attended at Maiwa with one of your guest presenters). I was concerned about the vapours/steam coming out of the pot when scouring. Is there any other alternative soap that can be used?

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  10. Re: morgen January 24:

    Synthrapol is a strong detergent and does contain a small amount of isopropyl alcohol. As such it is a chemical which one should wear rubber gloves when using. We recommend small amounts of synthrapol in all our recipes and when using in the washer or with warm water the vapors are not usually a problem. When used in scouring and simmered water where there are vapors a mask is good if ventilation is poor. Of course for pregnant women as asthmatics etc a completely natural detergent is advisable. Synthrapol is our preferred soap for scouring cellulose and after washing synthetic dyes but is not the only one that can be used. Soda ash is the more critical ingredient and the soap can be changed as long as it is able to help remove substances and does not put down a layer of anything that may interfere with dye bonding.

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    Replies
    1. Thank-you very much for your thoughtful reply. Is orvus soap an option?

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  11. Why is synthrapol not mentioned for scouring silk?

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  12. Orvus is very expensive. Is there an alternative or something I can make at home? I have Synthrapol, why can I not use that to clean the silk as well?

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  13. What about Rayon? Is it scoured the same way as Silk?

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  14. Some answers ... our appologies for the delay.

    Synthropol vs orvus. A lot of natural dye procedures involve preference and experience. Our preference based on our experience for protein fibres is orvus. We find some loss of sheen on some silks with synthropol which is slightly stronger.

    Economically they should be almost the same (on our site it is sythropol which is slightly more expensive). If you are happy with the results of scouring proteins with synthrapol there is no reason it may not be used. Rayon would be a cellulose fibre and would be scoured as such - it usually is much easier to dye than other cellulose fibres and would need slightly less scouring.

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  15. If scouring fabric in an enamel canning pot with synthrapol and soda ash, would it be safe to use that pot for canning in the future?

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  16. A good practice to maintain as a dyer is to keep studio gear and kitchen gear separate. This is a cautious step and good insurance agains accidents.
    However, to answer your question, if you are using the enamel canning pot to can sealed jars, you should be OK provided it is washed thoroughly. If you are scouring in an enamel pot be careful that there are no chips in the finish as the metal underneath may rust and spot your fabric.

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  17. I'm dyeing a "ready to dye" fabric that's 70% silk and 30% cotton. I may still scour it just to be sure. Would I use soda ash and synthropol or something else?

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  18. What about organic dying of linen yarns

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