DPG vs IPM: Which Solvent, When?

The base that carries a composition matters just as much as the composition itself. DPG (dipropylene glycol) and IPM (isopropyl myristate) are two distinct languages of that base. One softens the scent; the other anchors it to skin. Knowing which to call upon — and when — sharpens the signature of your formula.

DPG is a glycol derivative widely used in cosmetics: colourless, slightly viscous, nearly odourless. It dilutes fragrance oils, opens up the scent and balances cost. IPM, by contrast, is a fatty acid ester; it imparts a dry, lightly silky texture, spreads rapidly on skin and leaves no greasy film. The two come from different chemical families, which is precisely why what they dissolve — and fail to dissolve — differs.

To place a solvent correctly, you need to read its behaviour. Polarity (water-like attraction), viscosity (flow) and feel on skin are the three axes that govern your choice.

Pay attention to the density difference: there is a significant specific-gravity gap between DPG and IPM. Build your formula by weight (g), but when filling bottles by volume (ml), always convert using each solvent's own density. The same 100 g equals ~98 ml in DPG and ~118 ml in IPM. Skip this step and you will end up with overflow or underfill.

Solvent selection starts with the product format. What is inside the bottle? Will it be applied to skin or diffused into the air? The answer points you to the right solvent.

Choose DPG — for alcohol- or water-based compositions, diffusers and room fragrances, and cost-effective dilutions. The glycol softens the scent and keeps the blend homogeneous.

Choose IPM — for oil-based (anhydrous) perfumes, roll-on applications, and whenever you want a light, dry feel on skin. Its greatest strength is leaving no greasy film on contact with the skin.

Remember: the solvent alone does not determine longevity. How long a composition lasts depends primarily on the volatility of the raw materials within it. A citrus-dominant accord will dissipate quickly regardless of the solvent; heavy notes such as amber, oud and musk linger on any base. The solvent carries that balance — it does not create it. We explore the logic of concentration in greater depth in EDP vs Extrait: What Does Concentration Actually Change?

You have chosen the right solvent; now it is time to use it correctly. Whether you are making an oil-based roll-on or a diffuser blend, process discipline determines clarity and repeatability.

Even if a solvent appears "neutral", its safety and regulatory aspects must not be taken lightly. What matters here is not whether the source is natural or synthetic, but the molecule and the usage level.

IFRA limits are determined not by the total fragrance oil percentage but by individual ingredients, allergens and product category (leave-on / rinse-off) within the fragrance oil. Do not generalise with statements like "any solvent/fragrance oil is safe up to such-and-such a level." Read the IFRA compliance certificate and safety data sheet for every fragrance oil you use.

Avoid snap judgements in the natural–synthetic debate: some of the most strictly restricted allergens (Citral, Eugenol, oakmoss) are found in high concentrations in natural essential oils; natural bergamot contains phototoxic compounds that can cause skin discolouration in sunlight. Conversely, certain synthetics have an excellent allergen safety profile. We cover this topic in detail in Natural vs Synthetic: Safety, Cost and Performance.

On the product-notification side, keep the procedural steps separate from the question of liability: notification steps are a procedure; the obligations of the responsible person/manufacturer are a separate matter. For current procedures and regulatory requirements, refer to TİTCK official sources. For guidance on scale decisions, Inspired-By Perfume vs Private Label: Which Is Right for You? is a useful starting point.