A man came into the shop the other week, oil painter, twenty years at it, and asked me for "some of that thinner stuff, the one without the smell." Fair enough. I pointed him at the Sansodor. Two weeks later he was back, slightly cross, because his glaze layer was sitting on top of the painting like a puddle and refusing to dry.
He hadn't used the Sansodor wrong. He'd used the wrong thing entirely.
What he actually needed was a medium — something that goes into the paint and stays there, changing how it behaves. What he'd reached for was a solvent — something that thins paint out and then evaporates, leaving nothing behind. Both bottles look about the same on the shelf. Both have intimidating-looking labels. Neither manufacturer is in any particular rush to explain the difference, because they'd rather you bought both.
So this is the post I wish I could hand to him at the till. Four products that get talked about as though they're interchangeable — turpentine, Sansodor, Zest-It and Michael Harding's Miracle Medium — and what each one is actually for. Get it right and your oil paintings dry the way you expect. Get it wrong and you spend a fortnight waiting on a glaze that was never going to set.
The one distinction that matters
The simplest way to think about it is the difference between petrol and engine oil.
A solvent is petrol. You add it to the paint, it does its job — thinning the colour, washing the brush, flowing into the canvas weave — and then it leaves. By the time the painting is dry, the solvent is gone. It contributes nothing to the dry film.
A medium is engine oil. You add it to the paint, it does its job — softening the flow, lifting the gloss, slowing the dry, extending the colour for glazing — and then it stays. It becomes part of the dry film for the lifetime of the painting.
This matters because the wrong choice in either direction creates problems that don't show up for weeks. Put a medium where a solvent should go and you end up with the puddle problem above — too much oil in a lean layer, refusing to set, eventually cracking. Put a solvent where a medium should go and your colour mixes get watery and the painting loses depth.
The four products this post is about split cleanly along this line. Three are solvents — turpentine, Sansodor, and Zest-It. One is a medium — Michael Harding's Miracle Medium. Where it gets interesting is what each one does within its category, and why an oil painter in 2026 has more genuine choice than at any point in the last hundred years.
The three solvents at a glance
| Solvent | Base | Odour | Dissolves dammar? | Best for |
|---|---|---|---|---|
| Turpentine | Pine resin distillate | Strong | Yes — fully | Traditional dammar mediums |
| Sansodor | Refined mineral spirit | Low | No | Thinning and clean-up |
| Zest-It | Citrus terpenes (orange peel) | Pleasant citrus | Yes | Low-toxicity studio use |
Turpentine
The original. Distilled from pine resin since well before any of us were painting, traditional turpentine has the strongest solvent action of the three — it's the only one that will fully dissolve dammar resin, which makes it the only true choice for traditional dammar-and-stand-oil mediums. The English Distilled Turpentine we stock is the real article, not the hardware-shop substitute (which tends to be a mix of light petroleum fractions, sometimes sold as "turpentine substitute" or white spirit).
The downside is the smell, and what the smell is telling you. Turpentine contains alpha-pinene, a compound that some painters develop a sensitivity to over years of use. It's safe in a well-ventilated studio. It's not ideal at the kitchen table.
Sansodor
Winsor & Newton's low-odour solvent. Sansodor is, technically, a refined mineral spirit — the same family as white spirit, but with the strongest-smelling aromatic fractions stripped out. The result is a perfectly usable, smell-tolerant studio solvent.
The trade-off is that it's a weaker solvent than turpentine. It will thin paint, clean brushes, and wash a rag perfectly well, but it won't properly dissolve dammar resin. That means it isn't a true turpentine substitute for traditional medium recipes — if you're mixing your own stand-oil-and-dammar medium, you need real turpentine. For everything else, it's the obvious choice.
Zest-It
The interesting one. Zest-It is a UK-made citrus solvent built around terpenes extracted from orange peel. It has a pleasant orange smell rather than no smell, low toxicity, and — unusually for a non-turpentine — it will dissolve dammar. That makes Zest-It a genuine turpentine substitute for almost every traditional use, including in classic resin mediums.
It also doubles as a brush cleaner, and a better one than turpentine for that job, because it lifts dried paint more efficiently. Zest-It Limited is a small operation in Nottinghamshire that has been refining the formulation since the 1990s; the same family business has built out a full range of mediums and ancillaries around it. If you're painting at home, in a converted spare room, or with children in the house, this is the one I recommend.
The medium: Michael Harding's Miracle Medium
For most of oil painting's history, a "medium" meant some combination of oil, resin, and solvent — three ingredients, three jobs. The oil (stand oil, linseed) gave body and gloss. The resin (dammar usually) gave transparency and sped drying. The solvent (turpentine) thinned the lot to a brushable consistency.
Miracle Medium throws all of that out.
What's in the bottle is a plant-based ester oil — a thoroughly modern formulation built from renewable vegetable sources, with no resin and no solvent in it at all. It extends the flow of oil paint and lifts the transparency for glazing without changing the fundamental character of the paint, and crucially without introducing a resin layer that could yellow or crack over the long term.
The conservation angle is unusual for a commercial medium and worth flagging. Traditional dammar-based mediums are known to yellow as they age — most oil paintings from the last century carry some evidence of it. The ester-oil approach sidesteps that problem entirely. The dried film stays as flexible as the underlying oil paint, which matters particularly if you're painting on canvas rather than panel.
A useful detail: Miracle Medium also works as a brush cleaner at the end of a session, which can reduce solvent use further. Use one to three drops per brushload for normal painting, more for glazing, and remember that fat-over-lean still applies — this is not a substitute for thin solvent washes in early layers.
Michael Harding himself spent years refusing to make a medium; his position was that good paint on the right support, thinned only with more oil, didn't need one. Miracle Medium is what eventually changed his mind.
How to choose
Take the question one step at a time.
Do you need a solvent at all? If you're painting traditionally — lean underlayers, fat upper layers — then yes. You need something to thin the early stages and clean brushes between colours.
- Painting at home, smell-sensitive, kids in the house → Zest-It. The single biggest upgrade most home studios can make.
- Mixing your own traditional dammar-and-stand-oil medium → real English distilled turpentine. The dammar won't dissolve in anything weaker.
- Just need to clean brushes and thin a bit, want low odour, working in a small space → Sansodor.
Do you need a medium? If you want to glaze, extend flow without thinning the paint, or modify the surface character of your paint, then yes.
- Want a modern, solvent-free, conservation-conscious medium that won't yellow → Miracle Medium.
- Working in a traditional method and want to mix your own → look at the Zest-It linseed and stand oil range, plus dammar varnish and turpentine.
The combination question. Most working oil painters use one solvent and one medium — different jobs at different stages of the same painting. The most studio-friendly pairing we sell is Zest-It plus Miracle Medium. Together they take the toxicity out of a working studio almost entirely, with no loss of traditional handling.
Browse the range: all three thinners sit in our Oil Painting Solvents collection. Miracle Medium and our other studio-safe options live in Solvent-Free Oil Painting.
Frequently asked questions
Is Zest-It as good as turpentine?
For almost every purpose, yes — and for some purposes (brush cleaning, dissolving dried paint, low-toxicity studio use) it's better. The one exception is if you're specifically working with traditional dammar mediums and want absolute confidence the resin will dissolve to a perfectly clear solution. Turpentine remains the gold standard there.
Can I use Sansodor in traditional dammar mediums?
Not reliably. Sansodor is a mineral spirit and won't fully dissolve dammar resin. Use Zest-It or turpentine instead.
What's in Miracle Medium?
Plant-based ester oils derived from renewable vegetable sources. No solvent, no resin, essentially no smell.
Can I mix these together?
You can use a solvent and Miracle Medium in the same painting — different stages — but don't pre-mix them in a dipper. Solvent thins paint at the underpainting stage; Miracle Medium extends flow in the upper layers.
Are any of these flammable?
Turpentine and Sansodor are flammable and should be stored away from heat sources. Zest-It has a much higher flashpoint than turpentine and is far safer in storage. Miracle Medium is non-flammable.
Any questions on choosing the right solvent or medium for your work, drop into the shop on Callender Street or get in touch — happy to talk through it.
