Q&A on essential oils in thread conditioners

I'm not a trained textile conservator. I'm also not a scientist.

But a bad "feeling" – call it intuition, or just knowledge from past experiences - made me not want to use essential oils (EOs for short) when making my own thread conditioner, even before I officially started Sew Fine Thread Gloss. I've used EOs for a long time – for a variety of purposes – and I've had some last a long time, and some go bad, rancid, thicken, stain, etc. When making a product that I intended to use on threads and would come in contact with fabrics, on sewn items that I hoped would last for quite a while, the thought of using a potentially unstable substance, even in small quantities mixed with beeswax, made me worry.

Fast forward quite a few years.

I was asked to help finish an antique quilt – it had been started 39 years prior but never finished, by a woman whom I had never met, but I knew her husband from the local theatre group we were members of. He wanted to have it finished for their 40th wedding anniversary. All that was left was a little bit of hand quilting and binding, but when he brought it to me, there was noticeable staining from an unknown source. We have a wealth of textile and mill history in the surrounding areas that I live in, and through the Mississippi Valley Textile Museum, I was able to get in touch with someone who could help direct me with how to proceed (clean first then finish, finish first then clean, etc.).

Enter Lizz Thrasher.

With a background that ranges from kitchen management to auto restoration, Lizz has an unusual mix of technical and artistic skills. She formally trained in conservation and arts administration at Sir Sandford Fleming College in Peterborough, ON. Since starting her career as a conservator and museum professional, Lizz has worked in a variety of heritage institutions, including the Canada Museum of Science and Technology and The Klondike National Historic Site. Building on her skills as a sewist and knitter, she has cultivated an interest in historic textiles and textile conservation. In this capacity she has had the pleasure of working on objects from the City of Ottawa collection, the Mississippi Valley Textile Museum, and private collections.

Some of you may remember me posting this photo of the blast tunnel at The Diefenbunker in Carp, ON – the weirdest place I've ever went to chat quilting! Lizz works for The Diefenbunker as a member of their curatorial team, and it just happens to be close to my home, so I stopped in there with the antique quilt to get her professional opinion.

I've seen Lizz a few times over the years, most recently when the Mississippi Valley Textile Museum did a quilt conservation presentation to the Ottawa Modern Quilt Guild. And when I wanted to get a knowledgable opinion on my hypothesis on using essential oils in thread conditioners, she was the first person to come to mind. 

Questions and concerns.

I got in touch with Lizz and asked if she'd be willing to answer some of my questions (which would allow me to eventually publish this post). She obviously agreed, and I've outlined her answers below in a sort of Q&A form, as our conversation happened over a few back and forth emails.

Here's how our conversation progressed.  

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Jenn

I've always stayed away from using essential oils in [Sew Fine Thread Gloss] for fear that there might be some (be it minute) degradation of the fabric/thread one would be sewing with because essentials oils are (or were) a biological substance and degrade over time. In your experience, do you know of any studies, etc. that have "proof" that this may happen? ...any help/direction you could provide would be greatly appreciated!

Lizz

As far as I am aware, there really isn't a definitive study on the exact question "Do essential oils break down and affect adjacent textiles?", but there is a good bit of general conservation knowledge on aging oils.

There are existing samples of oils that have survived from Ancient Egypt and elsewhere and we can offer some understanding of how they behave over time. 

Oils first undergo oxidation, in which the material is broken down due to the effect of oxygen in the air. This causes a range of changes, including making the oil darker or changing its consistency. In cooking oils, this causes rancidity. If the oil is combined with other materials (including beeswax) this can change how well the mixture stays combined, and it can lead to the oil separating or changing the consistency of the mixture of which it is a part.

The second problem associated with oils is polymerization and crosslinking. After undergoing oxidation, some oils become polymerized, and dry out, taking on a rubbery or solid texture. The best example of this [is] the way in which natural oils are used to create oil paints in fine art: pigments and natural oils dry together to become solid layers. Crosslinking occurs when the long chains of molecules made by dried materials break apart due to the effects of oxidation and reconnect in different directions. This makes the material even tougher. Crosslinked materials are often very difficult to remove, and can be quite a problem on delicate surfaces.

If used in a thread conditioner: essential oils could cause the beeswax mixture to darken, separate or become gummy or sticky. These changes would also take place on the surface of the thread that had been coated. Over further time, the degraded thread conditioner could move into the sewn object and deposit onto the fabric itself, leaving stains. These stains will eventually become difficult, if not impossible to remove, and are often resistant to strong solvents.

By contrast, pure beeswax stays mostly stable for hundreds, if not thousands of years. It is unlikely to shift from the treated thread and is unlikely to cause staining. If there is a need to remove beeswax, it can be treated with chemical solvents and be removed from the fabric.

Jenn

This is such a fantastic and thorough answer! Thank you so much! Last technical question – aside from essential oils, I do include a small amount of Phthalate & Paraben free fragrance oil (bath & body safe) in the "scented" versions - no IFRA [International Fragrance Association] restrictions in terms of it blending with beeswax/separation, and no restrictions in terms of adding it to laundry detergents, fabric softeners, or including in fabric sprays. What are your thoughts on that?

Lizz

A fragrance is composed of two main parts: a carrier material and volatile compounds. Volatile compounds are let off into the air, creating the desired scent. The carrier keeps the scent in place, and can be a solid (like scented candles) or a liquid (like perfume). The nature of the carrier controls the rate at which scent is given off, creating scents that dissipate either very rapidly or very slowly. Scented candles smell for a very long time, while the scent of perfume can be gone in hours.

While commercially produced fragrances and essential oils are both scented products, using purpose-made fragrances differs from using essential oils in a couple of ways.

Let's take lavender, for instance. The lavender essential oil contains a number of compounds, in addition to the volatile compounds that make up the scent that we identify as "lavender". Fragrance companies isolate or synthesize these compounds to create a lavender scent that is recognizable and consistent in a way that "natural oils" cannot duplicate. In a natural oil, the quality of the flowers, the distillation process, and even the time of harvest can affect the quality and the scent of the oil.  

This is why commercially produced fragrances are carefully built using compounds and materials that are known to behave in set ways. A batch of  "Lavender Sachet Fragrance" will always smell and behave the same way every time because it is purposely made to do so. As we discussed earlier, an essential oil does not have this advantage, and can contain unwanted or even harmful materials.

Since the fragrances you are using are designed to be safe for skin and contact purposes, they contain regulated amounts of scent producing compounds.  Additionally, these are designed to be soluble in water, or in water and detergent. This is another way that fragrances differ entirely from essential oils. Essential oils can be completely insoluble in water or in water and detergent. 

In conservation, we tend to avoid using scented products for treatments, since some compounds in fragrances can breakdown and leave components that cause staining or other damage. This is mainly of concern in detergents and fabric treatments used in washing or in preparing for long term storage. 

Using a thread conditioner prepared with commercial fragrance in textile is a very minor exposure, and from a quick look at the Safety Data Sheets, and dilution rates for use in your application, there would be very limited amounts of fragrance that could theoretically transfer to a textile, and even then, these are designed to wash away.

So my recommendation as a conservator would be:

For absolutely heirloom pieces that you do not plan to wash or dry clean: use an unscented beeswax conditioner.

For any project that will be washed or dry-cleaned? Enjoy whatever [non EO] scent you like.

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I'm so fortunate that Lizz shared her knowledge and expertise with me and reaffirmed my decision to not use EOs in Sew Fine Thread Gloss. Knowing that all of you use a product that I create on your treasured quilts, garments and sewn makes is something that I don't take lightly. 

While a long read, I hope that this post has been interesting for you! 

xo – Jenn