DEP Oil Ratio for Agarbatti Dipping – The Definitive Guide for Incense Manufacturers

What Is DEP Oil and Why Is It Used in Agarbatti?

DEP oil — Diethyl Phthalate — is the standard carrier and diluent used in Indian agarbatti (incense stick) manufacturing. It serves three critical functions:

• Carrier: It dissolves and homogenises the concentrated fragrance compound into a workable dipping solution
• Fixative: It slows the evaporation of volatile fragrance molecules, extending the shelf life and burn longevity of the finished stick
• Absorption agent: It helps the fragrance solution penetrate deep into the bamboo stick during dipping, rather than sitting only on the surface

Without DEP (or a suitable alternative), fragrance compounds cannot be effectively applied to bamboo sticks at a practical cost.

The Standard DEP Ratio: 1:9

The Indian agarbatti industry standard is:

1 part fragrance compound + 9 parts DEP oil = 10% concentration dipping solution

In practical measurements:

• 100g compound + 900g DEP = 1,000g dipping oil
• 500g compound + 4,500g DEP = 5,000g dipping oil
• 1kg compound + 9kg DEP = 10kg dipping oil

This 10% concentration is the baseline for most standard agarbatti. It gives adequate fragrance strength at an economical cost for mass-market incense.

When to Adjust the Ratio

Higher concentration (12–15%) — Premium agarbatti

Increase the compound percentage when:

• Making premium or export-quality agarbatti that needs stronger throw
• Working with heavy base note compounds (oud, vetiver, resinous profiles) that benefit from higher loading
• The fragrance compound is inherently mild or has lower diffusion characteristics

At 12%: 120g compound + 880g DEP
At 15%: 150g compound + 850g DEP

Lower concentration (8%) — Economy agarbatti

Decrease the compound percentage when:

• Producing economy-grade agarbatti where cost is the primary constraint
• The compound is extremely strong or concentrated (some high-impact modern fragrance compounds are effective at 8%)

At 8%: 80g compound + 920g DEP

Do not go below 8% — below this level, most agarbatti will have insufficient fragrance and consumers will notice the weakness.

Choosing Quality DEP Oil

Not all DEP is equal. The quality of DEP directly affects:

• How well the fragrance compound dissolves and stays dissolved
• How deeply the fragrance penetrates the bamboo stick
• Whether the stick develops an off-note or cloudiness over time

What to look for in DEP:

• Purity: minimum 99% (pharmaceutical or industrial grade)
• Appearance: clear, colourless liquid — any yellow tint indicates impurities
• Odour: very mild, slightly sweet — strong or chemical odour indicates contamination
• Supplier: buy from established chemical suppliers with consistent quality batches

Avoid: recycled or blended DEP sold at unusually low prices. The cost saving on DEP is rarely worth the quality loss in the finished product.

Step-by-Step Dipping Process

1. Prepare your dipping oil

Weigh compound and DEP accurately using a digital scale. Add DEP to a clean stainless steel container first, then slowly pour in the compound while stirring. Mix for 5–10 minutes until completely uniform.

2. Mature the dipping oil (24–48 hours)

Seal the container and leave for 24–48 hours before use. This maturation step is often skipped but makes a significant difference — freshly mixed fragrance oil often smells sharp or unbalanced. After maturation, the molecules integrate properly and the dipping oil smells smooth and round, exactly as the finished agarbatti will smell.

3. Warm if necessary

If your compound contains waxy or resinous ingredients (common in sandalwood, oud, or frankincense compounds), the mixture may appear slightly hazy at room temperature. Gently warm to 30–35°C while stirring — this achieves complete dissolution without degrading the fragrance. Do not heat above 45°C.

4. Dipping

Pour dipping oil into a clean tray. Dip bamboo sticks slowly and completely — the entire stick should be submerged. Hold submerged for 2–5 seconds for standard sticks. Remove and allow excess to drip for 30–60 seconds before laying flat.

5. Drying

Lay dipped sticks flat on a clean, ventilated drying rack. Dry for 12–24 hours in a shaded, well-ventilated area. Avoid direct sunlight — UV exposure causes rapid degradation of fragrance compounds and can cause discolouration.

How Much Dipping Oil Per 1000 Sticks?

This varies by stick size and dipping method, but as a guide for standard 8-inch agarbatti:

• 1,000 sticks absorb approximately 80–120g of dipping oil total
• At 10% concentration, this means 8–12g of pure compound per 1,000 sticks
• For 10,000 sticks: approximately 800g–1,200g of dipping oil (80–120g compound + 720–1080g DEP)

Run a small test batch to calibrate your specific setup — stick diameter, dipping time, and compound viscosity all affect absorption.

Alternatives to DEP Oil

While DEP is the standard, some manufacturers use:

• DOP (Dioctyl Phthalate): Slightly higher boiling point, can be useful for very premium incense where slower release is desired. More expensive than DEP.
• Mineral oil (white oil): Used by some natural/organic agarbatti makers who want to avoid phthalates. Gives slightly different fragrance release profile.
• IPM (Isopropyl Myristate): Premium carrier, used in high-end agarbatti. Excellent absorption but expensive.

For most standard Indian agarbatti production, DEP remains the most practical and economical choice.

Buy Agarbatti Fragrance Compounds for DEP Dilution

LargAroma (Sai International Perfume) supplies 30+ ready-to-use agarbatti fragrance compounds optimised for 1:9 DEP dilution. All compounds are tested and formulated for standard Indian agarbatti manufacturing conditions.

Browse our compound range: Agarbatti Fragrance Compounds at LargAroma