The DIY Perfume Lab

99 Bottles of Tonic on the Wall ...

Niagara Apothecary in Niagara-on-the-Lake, Ontario

Designing Your Workspace

When designing your workspace, one of the first things to consider is air quality. Essential oils and aroma chemicals are, of course, smelly! Good ventilation and odor containment are important considerations when setting up your lab. For your own health, and also for your ability to detect differences between scents, you need to keep the fragrant “noise” to a minimum. Some options to consider:

  • Install an exhaust fan (like the kind you find in bathroom ventilation).
  • Manage the trash. Use a can with a lid that seals.
  • Store raw materials in cabinets with doors that shut (glass or plastic doors allow view of bottles).
  • When testing perfumes on scent strips, consider using a bell jar, or a homemade one out of plastic bottle.
  • Wear disposable latex gloves to avoid contaminating your fingers.

Your “bench” or worktable may be subject to aroma chemical spills from time to time, so choose a non-reactive, non-absorbent surface that’s easy to clean. Some options:

  • Stainless Steel – food prep tables from restaurant supply companies work well, for example.
  • Formica
  • Glass top – tempered is best.

Refrigeration. Some aroma chemicals, like the citruses, will have a longer shelf life when refrigerated. Consider getting a mini fridge or a wine fridge.


Lab Equipment List

Lab Notebook – Always take notes. Take notes when smelling and familiarizing yourself with a new chemical. Take notes as you formulate a new blend. Note what works, note what doesn’t. Note everything.

Digital Scale accurate to 0.01g – Perfume industry professionals measure raw materials by weight. Ohaus makes a pricy but nice scale. And there are less expensive options, too. Several good people on Basenotes recommend this one from Old Will Knot that seems to have all the right features at a good price.

Tiny Glass Beakers – If you are working by volume (many recipes are in drops/ml), you’ll want to be able to measure accurately in ml. Look for beakers with small graduations (10, 15, 30 ml). You can find these at lab supply companies or nifty vintage beakers on eBay. These 25 ml graduated beakers at Aqua Oleum in the UK are some of the most ideal beakers I’ve seen, and very reasonably priced.

Pipettes or droppers

Stirring rods

Tiny funnels. You can also get them in glass.

Fragrance Tester Strips

And maybe something like this to hold all those test strips, or like this. Or possibly this. I’ve also heard you can use chopstick rests.

Casseroles – for melting small quantities of beeswax if you are making solid perfumes.

Curettes for scooping out viscous and resinous absolutes like vanilla, benzoin, and fir. You can find them in bamboo or stainless steel.

Hot Plate
If making solid perfumes, you will need a heat source. You can work over your kitchen stove with a double-boiler – or if you’d prefer not to work in your kitchen, you can get a hot plate as an alternative heat source. There are a range of options.

Education for the Aspiring Perfumer

Classes and Schools
Laurie Erikson of Sonoma Scent Studio has an excellent list of Perfumery Classes and Schools around the world. Pia Long, a Finnish perfumer in England, followed a non-traditional route and writes a lovely account of how to become a perfumer and her own personal journey.

Online Forums

Blogs / Web sites

Books

  • An Introduction to Perfumery by Curtis and Williams
  • Perfumery: Practice and Principles by Robert R. Calkin and J. Stephan Jellinek
  • Perfume: The Alchemy of Scent by Jean-Claude Ellena
  • The Diary of a Nose: A Year in the Life of a Parfumeur by Jean-Claude Ellena
  • What the Nose Knows by Avery Gilbert
  • Perfumes: The A-Z Guide by Luca Turin and Tania Sanchez
  • Essence and Alchemy: A Natural History of Perfume by Mandy Aftel
  • Fragrant: The Secret Life of Scent by Mandy Aftel

Perfume Samples

Recipes, Formulas, and How-To’s

Supplies for Creating Perfume

Perfume Organ

Perfume Organ, Fragonard Perfume Museum, Paris by Nico Paix

Beginner’s Kits

Raw Materials – Naturals

  • Aftelier* – Quirky selection of unusual perfumers botanicals. Fast shipping. No minimum.
  • Aqua Oleum – Excellent UK source for essential oils from Julia Lawless.
  • Aromatics International – Expensive oils connected with the Aromahead Institute. Site has excellent information.
  • Eden Botanicals* – EOs, CO2s, Absolutes. Excellent quality, wide selection, no minimum purchase.
  • Enfleurage – Aromatics from the natural world. Specialize in Frankincense. Also offer hydrosols and more.
  • Liberty Natural Products* – Amazing selection. Includes isolates and more. $50 minimum.
  • Mountain Rose Herbs – Wide selection. Somewhat expensive shipping. (Mentioned more often by home aromatherapists than perfumers. Never tried.)
  • Nature’s Gift – Just tried them for the first time for more aromatherapy-type oils. Also have wide selection of hydrosols, carrier oils, waxes and butters. Well researched and reasonable prices.
  • White Lotus Aromatics* – Gorgeous, superior quality naturals personally sourced from around the world. $100 minimum.

*Companies with an astrix * are the ones I order from most frequently. Eden Botanicals is my “go to” supplier.
Also helpful: Providence Perfume offers a useful review of some of the best/worst essential oils she’s ever purchased.

Raw Materials – Synthetics

Beeswax

Carrier Oils
Carrier oils are for making oil-based perfumes, solid perfumes, or other body products. Do not add them to alcohol-based perfumes (they will separate and make a mess). Some carrier oils will go rancid fairly quickly. Fractionated coconut oil and Jojoba oil are two of the longest-lasting.

Alcohol
For alcohol-based perfume, use perfumer’s alcohol a.k.a specially denatured (SD) alcohol, which is 95% ethanol that has been denatured with an additive. The denaturing is done for regulatory reasons to prevent consumption. When purchasing perfumer’s alcohol in the United States, use 40b, which is denatured with t-butyl alcohol & Bitrex. Do not use 39c, because it contains diethyl phthalate (DEP), a.k.a. phthalates for which there are serious health concerns. For natural perfumers, there are also organic alcohols that have been denatured with natural materials. If you are not planning to sell your perfume, you can also use Everclear / Pure Grain Alcohol instead of Perfumer’s Alcohol. It should be 190 proof (95% alcohol) ethanol. In the USA, PGA is available for purchase in some states but not all. Some natural perfumers will also use Vodka for perfume, but it’s not as desirable as Everclear/PGA due to the lower alcohol content. For cleaning, you can use Isopropyl alcohol, Vodka, or PGA.

Dipropylene Glycol (DPG)
DPG is an odorless, colorless synthetic carrier oil that is perfect for diluting fragrances to 10% or 1% to be used for sniff tests / educating your nose. It is oil-based, but water and alcohol soluble.

Bottles and Packaging

Essential Oil Safety

Vintage Pharmacy, Dripping Springs

Vintage Pharmacy, Dripping Springs by Dave Wilson

Yes, essential oils are all-natural and they come from plants. But nature makes all kinds of dangerous and toxic things, so it’s best to use caution and follow safety guidelines.

The main thing about essential oils is that they are extremely concentrated plant essences, a.k.a. chemicals. Some of them are skin irritants, mucous-membrane irritants (try accidentally rubbing your nose with cinnamon EO sometime – you wouldn’t wish it on your worst enemy), photo-sensitizing (many of the citruses can cause reactions in the sun), or even toxic (hello, absinthe).

Robert Tisserand is the guru for essential oil safety, but his classic safety reference is massive and geared more towards professional aromatherapy practitioners. For the lay person, Kathi Keville’s and Mindy Green’s Aromatherapy: A Complete Guide to the Healing Art has a very helpful chapter that covers the safety basics, and Julia Lawless’s The Illustrated Encyclopedia of Essential Oils has wonderful information for each individual plant. The info below is mostly taken from Keville’s and Green’s book.

General Rules of Thumb

  • Use high-quality, pure oils. There is an incredible amount of poor-quality stuff out there. Choose your suppliers with care.
  • Do not use oils “neat,” or undiluted on the skin. There are two exceptions to this rule – lavender and tea tree oil, for very specific spot-applications.
  • Safe aromatherapy dilution is 2%. This is 10-12 drops EO / 1 oz carrier oil. (Most perfume dilutions are higher, a natural perfume might be closer to 10%, but application typically involves smaller surface area of skin.)
  • Keep away from eyes and mucous membranes. Ever touched your eyes after chopping a jalapeno? Yep, that was an essential oil.
  • Test for sensitivity. Even diluted, some oils can a reaction. If in doubt, try a patch test in the crook of your elbow at 2% dilution (10-12 drops EO / 1 oz carrier oil).
  • Understand photosensitivity. Many citruses naturally contain the chemical bergapten and can cause a reaction to the sun. Good suppliers have warnings for these oils. It’s no big deal if you’re using a tiny amount in a perfume, but you might think twice before using in a lip balm. You can also buy “bergapten-free” oils, which eliminates the problem.
  • Do not take orally. Seriously, this is a great way to burn your mouth. That said, you can use them to cook with, if you know what you are doing. Herbs have essential oils too, just much less concentrated. So, when added to recipes in the right amounts, essential oils are dilute and harmless. Keville and Green’s book has some fun suggestions.
  • Keep out of reach of young children. Some oils smell sweet and delicious. Little people may want to drink them.
  • Be careful when using with children, pregnant women, the elderly, and people with severe or chronic illness. They are more sensitive, so smaller dosage / milder dilutions are required. Use a 1/2% (2-3 drops / 1 oz carrier oil) to 1% dilution (5-6 drops / 1 oz carrier oil). Also, some essential oils are contra-indicated for certain conditions, including pregnancy, diabetes, high blood pressure, etc. So read up on each essential oil before use.

Guidelines for Use with Children

  • Safest essential oils for children: lavender, tangerine, mandarin, neroli, frankincense, peititgrain, and Roman Chamomile.
  • Use 1/4 to 1/2 the adult dosage. This is 1/2% (2-3 drops / 1 oz carrier oil) to 1% dilution (5-6 drops / 1 oz carrier oil).

Guidelines for Use with Pregnancy

  • Safest essential oils for pregnant women: rose, neroli, lavender, ylang ylang, chamomile, citrus (bergamot, grapefruit, lemon, lime, mandarin, orange, petitgrain, tangerine), geranium, sandalwood, spearmint, frankincense.
  • Many sources disagree on what’s safe. When in doubt, pregnant women should “follow their nose” – if something smells unpleasant during pregnancy when senses are heightened, then it’s best to avoid it.
  • Use a 1/2% (2-3 drops / 1 oz carrier oil) to 1% dilution (5-6 drops / 1 oz carrier oil).

Measurement Conversion Chart

When working with essential oils, the most common conversions you typically need are:

  • 20 drops = 1 ml
  • 100 drops =1 tsp = 5 ml
  • 300 drops = ½ oz = 15 ml
  • 600 drops = 1 oz = 30 ml

But, sometimes a little more detail is in order:

Drops Teaspoons Ounces Drams Milliliters
10 drops 110 tsp 160 oz ~18 dram ~½ ml
12 12 drops 18 tsp 148 oz 16 dram 58 ml
25 drops ¼ tsp 124 oz 13 dram 1 ¼ ml
50 drops ½ tsp 112 oz 23 dram ~2 ½ ml
100 drops 1 tsp 16 oz 1 13 dram ~5 ml
150 drops 1 ½ tsp ¼ oz 2 drams ~7 12 ml
300 drops 3 tsp ½ oz 4 drams ~15 ml
600 drops 6 tsp 1 oz 8 drams ~30 ml
24 tsp 8 tbsp 4 oz ½ cup ~120 ml
48 tsp 16 tbsp 8 oz 1 cup ½ pint
96 tsp 32 tbsp 16 oz 2 cups 1 pint

Source: Aromatherapy: A Complete Guide to the Healing Art by Kathi Keville and Mindy Green.

This chart makes the common assumption that 20 drops = 1 ml. However, always remember that drops vary in size based on liquid viscosity and the dropper or pipette you are using. If you want certainty, conduct a test with a calibrated beaker to see how many drops = 1ml.

For example, in Mandy Aftel’s book, Essence & Alchemy, she assumes that 40 drops = 1ml. Double the common assumption! I recently tested this myself using a glass eyedropper and found it to be absolutely accurate. So definitely check before moving forward with a recipe or formula.

Eden Botanicals offers a more detailed range for how many drops = 1 ml, and so far this matches my experience as well:

1 ml = 30-50 drops, depending on viscosity and size of the drop; aprox. 40-50 drops per ml for very mobile oils such as some citrus oils and fir needle oils; more viscous (thicker) oils such as Vetiver and Sandalwood will be approx. 30-40 drops per ml.

1 oz = 30 ml. Using these measurements, it can be extrapolated that there are approx. 900-1500 drops per ounce.

Notice how there are more than double the number of drops in the first estimate (600 drops = 1oz) and the Eden Botanicals estimate (900-1500 drops = 1oz)? Yikes.

This variability is why professional perfumers measure in weight with accurate lab scales. Still, if you’re just messing around at home, drops are far easier and most beginner recipes are calculated in drops. For more conversions, try this handy Volume Unit Converter site.

Aging Perfume Blends

Aging

Aging by Bob AuBuchon

I’m not a particularly patient person. So – ARGH! – I was horrified to discover that in this perfume crafting business you need to let a blend age to let the scents marry. Fragrances will change as they mature, and after aging they become much more seamless, rounded, and soft.

Le sigh.

Advice about this process varies. Generally speaking, there are two times you can age a blend: before and after dilution.

Which brings up another point: Most people advise combining your raw materials to create your fragrance blend first, prior to adding it to your carrier medium.

After mixing your blend of raw materials, store it in a dark bottle in a cool place to let it age. Sources vary on how long. Some DIYers seem to skip this step, others recommend anywhere from 1 week to 2-3 weeks.

The most commonly given advice seems to be 48 hours to 1 week, averaging out at around 4 days.

Then, sniff the blend. If you’re happy with it, dilute with a carrier oil (jojoba or fractionated coconut oil are best; they have the longest shelf life of oils) or perfumer’s alcohol (much better shelf life than oils – basically indefinite).

After dilution, most sources agree you need to let an alcohol-based perfume age 4-6 weeks. For an oil-based perfume, try 3 days to a week.

Oh, the waiting! I guess I’ll have to get used to it.

Update:

  • In Essence & Alchemy, Mandy Aftel recommends letting an alcohol-based blend mature for at least a week, and up to a month if you can stand it (this is after dilution).
  • In Perfume: The Art and Craft of Fragrance, Karen Gilbert recommends letting an alcohol-based blend macerate for a week or two before using.

Grapefruit Rose Solid Perfume

Ella's Grapefruit RoseMy 5 year-old daughter loved the Bulgarian Rose when we were doing the “Rose sniff test” and asked to make a solid perfume out of it. Why not?

I originally wanted to do something with top, heart, and base notes, but the only scent she liked other than the Bulgarian Rose was Pink Grapefruit. Everything else – from Benzoin to Ylang Ylang – elicited a strong, “Blech. Yuck Mommy!”  Or even, “That one smells like tulips sprayed with skunk powder!”  So! Grapefruit and rose it is. Here’s how we made it.

Ingredients
8 ml Jojoba oil
1/2 tsp grated beeswax
14 drops Bulgarian Rose Absolute
10 drops Pink Grapefruit Essential Oil

Steps

  1. Pour the Jojoba oil into a small beaker.
  2. Add the essential oils to the beaker and stir with a glass stirring rod.
  3. Next, add a heaping 1/2 tsp of grated beeswax to a small lab casserole (or other porcelain or glass container), and melt it over a hot plate or double boiler.
  4. Then pour the oil into the melted wax and stir to combine as quickly as possible. You don’t want to overheat the perfume and burn off the top notes.
  5. Pour the liquid perfume into a 1/2 oz tin or other container. Close it immediately and let it sit for 10-15 minutes to cool before you touch it.

How does it smell?
Sweet, happy, and round, and very rosy. At first it’s hard to detect the grapefruit relative to the rose – they blend together well – but it’s there. I wouldn’t really call it a perfume so much as a “pleasant scent.” My daughter loves it though – and that’s what’s important.

Notes for Next Time
This blend is relatively safe for children – rose and grapefruit are two essential oils that are very kid-safe with positive effects on mood (this is a super happy scent), though I think the concentrations in the solid perfume are a bit high compared to standard aromatherapy dilutions. I’m not too concerned since my daughter just dabs a little on every once in awhile.

Aesthetically, if I were to do this again, I’d add more top notes (since solid perfumes pretty much devour top notes) so the grapefruit is more prominent and decrease the rose. I’d also add a base to increase longevity. This vanishes in about 30 minutes to an hour.

Amber Spice Solid Perfume

IMG_4179

Experiment No. 1: Amber Spice Solid Perfume from Fragrant by Mandy Aftel. Out of respect for the author, I won’t publish the amounts – you’ll need to buy the book for that. But I will tell you what supplies you need, how to do it, and and how it turned out. What I like about Mandy’s recipes is that they are the perfect “experiment” size. They fit neatly into a 1/2 oz metal tin. No waste!

Raw Materials

  • Labdanum Absolute
  • Cinnamon Essential Oil
  • Rose Absolute (optional)
  • Lime Essential Oil

Carrier Media

  • Jojoba Oil
  • Beeswax

Equipment

  • Fragrance tester strips
  • Cheese grater (for grating wax)
  • Measuring spoons
  • Glass eyedroppers or pipettes (minimum 1 per EO)
  • Tiny graduated beaker or cylinder – smallest graduations you can find
  • Glass stirring rod
  • Lab casserole dish (80 ml size works great)
  • Hot plate (optional – you could also work over your stove)
  • Paper towels
  • Shot glass of Vodka or Everclear for dropper cleanup

Packaging

  • 1/2 oz flat metal tin
  • 1.2″ circle label

Steps

  1. First, I tested each of my raw materials by placing a single drop on a labeled fragrance tester strip. It’s helpful as I’m learning to smell each oil individually – to discover the shape of the material itself, its intensity, longevity, etc.
  2. Next, I set up my work area and laid out everything I needed in easy reach. Paper towels everywhere in case of spills.
  3. I poured the Jojoba oil into the graduated beaker, and then added the essences to it. Be very careful to use a new dropper for each oil, and put used droppers into the shot glass of alcohol to clean them. You want to be extra careful not to cross-contaminate your oils.
  4. I added grated beeswax to the lab casserole, and melted it over a hotplate. Once melted, I added the oil + essences, and stirred together as quickly as possible and removed from heat.
  5. Finally, I poured the perfume into the tin, capped it, and waited 15 minutes for it to solidify. Finis!

Notes on Materials

How did it smell?
Quite nice, actually. It’s amazing how well the scents meld to create a new thing. The top and base notes were most prominent to my nose.  A good strong hit of lime up top that fades fairly quickly, and the labdanum makes a sweet, leathery, ambery base that is apparent throughout the arc of the perfume and into drydown. At first, I had a hard time picking out the cinnamon – where was the cinnamon? But I realized it had been transformed into a sparkling, hot brightness that did not read as “cinnamon.” Nice. I could not find the rose at all. Perhaps it was rounding things out, or perhaps it was simply buried. Overall, it felt unisex – perhaps leaning slightly masculine. Wears soft and close.

My husband (not a fumehead) had an interesting insight. One sniff, and he said, “Cherry coke!” That puzzled me for a minute, then I looked up the formula for the original Coca-Cola – and sure enough, there was a lime-citrus-cinnamon combo.

Coca-Cola Formula

2 drops lime essential oil
2 drops orange essential oil
1 drop lemon essential oil
1 drop nutmeg essential oil
1 drop cinnamon essential oil
2 teaspoons vanilla extract

– From Fragrant

Mistakes and Questions

  • I spilled the Jojoba. How on earth does one pour out of a Boston round without sloshing?
  • Need to be careful to get all the perfume oil out of the beaker.
  • Cheap hot plate was ok but it smoked unpleasantly – need to clean?
  • How do you clean the droppers?! I got a trace amount of cinnamon oil in the cap of a dropper, and then after bathing them in Everclear, I ran all my droppers and caps through the dishwasher to sterilize. Now ALL of the smell like cinnamon. I curse you, cinnamon!

What Worked

  • 80 ml lab casserole was a great size to work with
  • Vintage 10 ml graduated beaker with 2 ml increments was also perfect choice
  • 1 eye dropper per raw material, with a shot glass to park them in afterward
  • glass stirring rod
  • 1/2 oz tin and 1.2″ circle labels = perfect size
  • OXO grater with attached box = awesome for grating beeswax and storing it
  • Paper towels = unglamorous but vital

That’s all for now!

Compartive Study: Rose Absolutes

Rosa damascena

Rosa damascena “Jacques Cartier” (Moreau Robert 1886 ) by Patrick Nouhailler

The first recipe I want to make calls for “Rose Absolute” – and ah, that can mean so many things! Figuring that there’s no such thing as “too much rose” I ordered three different small samples when I was stocking up on essential oils.

To test them, I put a drop of each on its own fragrance tester strip and sniffed, made notes, rested my nose, sniffed again, made more notes.

Rose de Mai Absolute

It’s amazing the degree of variation in such similar materials. The most unique one was “Rose de Mai” – which makes sense, as it’s a cabbage rose, Rosa centifolia, a slightly different species than the other two, which are both Rosa damascena.

Although this particular essence came from roses grown in Egypt, “Rose de Mai” is the rose famously grown in the region of Grasse, France and so it’s intimately connected to French perfumery. The liquid itself was the lightest in color, a light green-yellow, with a piquant, fresh, sweet, and a lightly spiced / peppery character with hints of green. This is a sprightly rose, rather than a sultry sexy rose – I found it to be my favorite, and also the most unique. It seemed..individual, pretty – but perhaps a bit unwilling to blend? It has its own precise character. And while the scent was strong, after I had smelled the other roses, I found myself unable to pick it up after I had sniffed the others, and so I wondered if it would bury easily when mixed with other strong scents. On the tester strip at least, it turned out to be surprisingly tenacious, given its “airy” character. Another thought: it immediately brought to mind Serge Lutens’ Sa Majeste la Rose.

Rose Absolute, Bulgaria

Bulgarian rose has a reputation for being most prized among perfumers. My 5 year old daughter immediately named this one her favorite. “This one smells strong! I like strong smells!” Wow, this is a rosy ROSE!  From my notes: Spicy, sweet, more vegetal than Rose de Mai – less light/fresh/green – denser, fruitier, apricot(?) – STRONGER, more savory. A maximum strength ROSE – the classic, straight up and intense. ROSE ROSE ROSE. Dark orange-red juice. Not a fussy and fickle beauty like Rose de Mai. This damask rose from Bulgaria was more a gorgeous country girl, rosy cheeked and sturdy, strong and beautiful. It turned out (not surprisingly) to have the best tenacity.

Rose Damascena Absolute, Turkey

From my notes: Beautiful! Fruity, sweet, jammy. A honey rose, soft, round, and mellow. Yellow-orange juice. Since the recipe I want to make is not a floral blend at all (rose plays only a supporting role) – I chose this one since it seems like it may blend well and round things out. This one had the least tenacity on the tester strip though.

Beginning with Mandy Aftel

Mandy Aftel's Fragrant: The Secret Life of Scent

I suppose I have to begin somewhere, right? The world of fragrance is like a forest – it’s easy to get lost. When wandering, it’s best to have a guide. When I first starting smelling all the smells (sniffing all the sniffs?) I read Luca Turin’s and Tanya Sanchez’s Perfumes: The A-Z Guide and sniffed along with the help of samples from Luckyscent, The Perfumed Court, and Surrender to Chance. I didn’t agree with everything that Turin and Sanchez said, and yet – by using their ideas as a North Star, I was able to begin sampling dozens, then hundreds of perfumes (yes, really, hundreds – the sampling habit became rather addictive! not that I’m sorry…), and as I followed along I understood more of what I was encountering.

Similarly, now that I’m dabbling in the world of DIY fragrance, I have to put my toe in the water somewhere, so it might as well be with Mandy Aftel. Aftel is a bit like the Alice Waters of natural perfumery – she takes French ideas, peels them back to their simplest and most essential forms, and make them accessible, natural, Californian, and relaxed. I’d had Essence & Alchemy on my shelf for ages, and never quite made time to read it – and then, when the urge to mix my own scents suddenly hit – I devoured it in a few days, then moved on to Fragrant.

So, I’ll be taking Mandy as my Beatrice, my first guide on what is likely to be a long and circuitous tour. Both books are a pleasure to read – modeled, I’m guessing, after some of the wonderfully hodge-podge alchemical texts Aftel has in her collection. There’s a lot of lore, history, and delicious information – sprinkled here and there with recipes, some old, and some Aftel’s. Fragrant in particular, structured as it is around cinnamon, mint, frankincense, ambergris, and jasmine, lends itself to being a beginner’s cookbook of natural perfumery. For each essence, there is a recipe for a solid, oil, and alcohol-based perfume – so that it’s really possible to explore the nuances of each scent and how it morphs in different carrier media.

I’ll take these as a guide for conducting some of my first experiments…and we’ll see where things go from there.