15 E & F, Sri Venkateshwara Co-Op. Industrial Estate


IDA, Jeedimetla, Hyderabad 500055 AP INDIA
Ph: +91-40-23091650, 23096104
Fax: +91-40-23097040

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Solvosol Paints Pvt. Ltd.


Why Polyurethane Coatings?

A comparison between Apus-cured urethanes with two component urethanes & two component epoxies

Apuscured Urethanes

Moisture Cured Urethanes

Apus-Cured Systems

Apus-Cured Other Special Features


A Critical Comparison AC-TAR or AC-Zinc Vs COAL TAR Epoxy

Uses Where AC Urethanes have Advantage


K. Venkateswarlu

Graduate in Chemical Engineering from Andhra University and a Post Graduate from IIT, Kharagpur with specialisation in Petroleum Refinery Engineering and petrochemicals. Worked with the Paints Division of ICI for 12 years and then with Nagarjuna Group for 10 years, before resigning in 1992 as General Manager, Exports. Trained in U.S.A. and Malaysia on Polyurethane and Acrylic Coatings.

Travelled extensively abroad and all along associated with Corrosion and Corrosion protection through surface coatings. Participated in a number of seminars in the above field. A major part of the 22 years of industrial experience is devoted to special coatings like Polyurethanes, Epoxies and Acrylics. He was also a Consultant to Tata Exports Ltd.

Solvosol Paints Pvt. Ltd. is a company engaged in the manufacture of a variety of surface coatings, including coating systems on a turnkey basis for highly specialised applications.

The company promoted by Technocrat Entrepreneurs, has specialised in the Polyurethane, Acrylic, Epoxy and Alkyd Resin systems and makes coatings (paints) putties, sealants, caulking compounds, adhesives and customised coatings tailor-made for individual needs.

Summarising, we have developed and established the following successfully.

Conventional Two Pack Poly Urethanes

Blocked Poly Urethanes

Moisture Cured Urethanes

Urethane Alkyds

Polyols, Adducts & Urethane resin systems

Heat Resistance Coatings up to 600°C

Sealants & Adhesives

Floor Coating Systems

Ceramic Coatings


Both Isocyanate & Isocynurate foams

Cathodic Depositable Water based Poly Urethanes

Low Temperature Baking Water based Poly Urethanes

Road marking coatings

Coatings for the ID of the pipe lines

Re-bar coatings

Wood Lacquers and Laminates

Coatings for effluent treatment plants

TopWhy Polyurethane Coatings?

The following are the considerations of Polyurethane Coatings which show superior coating performance compared with epoxy coatings or fusion bonded epoxy coatings, so it was decided to formulate Polyurethane coatings:

Excellent resistance to atmospheric exposure

Excellent adhesion

Non-Chalking, Non-Yellowing

Easy to clean

Very good resistance to chemical and water

Resistance to Mineral, Vegetable Oil, White Spirit, Paraffin, Petrol, etc

Extremely tough and abrasion resistance

Quick drying

Wide choice of raw materials as compared to epoxy, including tightly bound rust and old paint

Excellent application characteristics by brush roller or spray

Resistance to Micro-organism is good because polyurethanes contain free isocyanate groups, which are poisonous to micro organisms

Economical cost wise for longer period

TopA comparison between Apus-cured urethanes with two component urethanes & two component epoxies

S. No.

Apus-Cured Urethanes

Two Comp Urethanes

Two Comp Epoxy


No pot life, no catallyzation, no mixing of plural components

Short pot life

Short pot life


Can be applied in humidity to 99%

Not above 85%

Not above 85%


No dew point restriction

Must be a minimum 50F above dew point

Must be a minimum 50F above dew point


Can cure down to 200F

Not below 40-500F

Not below 40-500F


Highly recommended for immersion. Can be immersed within 30 minutes

Not recommended for immersion

2-6 days cure before immersion


Can be applied to damp Surfaces

Not recommended

Not recommended


Excellent colour and gloss typical of aliphatic urethanes


Not recommended for exterior exposure w/o topcoat


Best corrosion resistance. Formulations available to give 20,000 hour ASTM salt spray resistance.

Used only as top coat

Not as good


Best Zinc-Rich Vehicle. Out performs inorganic Zinc when top coated

Not recommended

Not as good

TopApuscured Urethanes

Popularly known as Moisture Cured Urethanes

State of the Art Technology

Technology not available in India

Ideal for atmosphere where relative humidity is beyond 80%, where other coatings fail

No sand blasting required

TopMoisture Cured Urethanes

MC Urethanes comes under ASTM Type II, single pack classification. These are NCO-terminated pre-polymers with the NCO percentage ranging from about 2 to 15%. Normally these are low solid coatings, solids varying from 40 to 60. The chemistry of the MC Urethanes involves the reaction of the diisocyanate with the hydrogen donors, leaving a slight excess of NCO available to react with the atmospheric moisture. These NCO groups react with any moisture available to form substituted or disubstituted ureas and biuret groups. These products are in use for almost 25 years. These coatings are most useful in any application calling for an extreme resistance to abrasion, for areas that require good elongation to withstand expansion and contraction of a substrate and for many chemical environments. Perhaps the major advantage of the MC Urethanes is that they are a one component material, ready to use as it is removed from the can. No mixing, measuring, weighing or additives are necessary.

The high relative humidity and presence of mono layer of moisture are two of the major problems associated with painting on marine installations. Most significantly these problems turn out to be assets for MC systems as they require a minimum relative humidity of 45% and up to 80% they perform exceptionally well.

Based on the literature available and our own R & D, we have evaluated Epoxy, Two Pack Conventional Urethanes and MC Urethanes for various applications in marine/saline atmospheres.

TopWe have given importance to the following factors

High strength with matching elongation

Very low permeability to air and moisture

Excellent resistance to Marine atmosphere and sea water in alternate wet and dry conditions

Very high adhesive strength and scratch resistance

Faster turn around time

Life spanning 3 to 5 years and 5 to 7 years depending on the end use

Difficult working conditions like narrow spaces

Low inventories

TopApus-Cured Systems


Manual/Power Tool Cleaning

One coal of Apus cured clear

Two coats of Apus cured under coat

Two coats of Aliphatic finish based on MIo/Plain

On customer request we can replace MIO to give straight shades

TopUnder Coats

Apus Cured Zinc

Apus Cured Zinc MIO

Apus Cured Tar

Apus Cured MIO Tar

Apus Cured Mastic

TopFinish Coats

Aromatic MIO finish

Aromatic Plain finish

Aliphatic MIO finish

Aliphatic Plain finish

Aromatic Aluminium

Aliphatic Aluminium

Ceramic Putty

TopApus-Cured Other Special Features

Extremely hard, but flexible

Very Low permeability, no substrate attack

Exclusive formulations for PH above 7 and below 7

Of the above three, MC Urethanes appears to be the best. The MC Urethanes have shown outstanding properties compared to conventional Two Pack Urethanes. MC systems are used widely abroad, especially in USA.
AC Zinc outperforms inorganic zinc silicate in all respects.

TopA Critical Comparison AC-TAR or AC-Zinc Vs COAL TAR Epoxy

Advantages of…

S. No.

AC-Tar or AC-Zinc

Coal Tar Epoxy


AC-Tar and AC-Zinc can be applied at temperatures as low as -50C, humidity to 99%, no dew point restriction.

Cannot be applied for humidity above 80-85%, or temperature below 70C.


AC-Zinc and AC-Tar can be immersed within 30 minutes.

Required 2-8 days prior to immersion.


Both can be recoated or touched up at any time without special treatment.

Cannot be recoated after 12-36 hour unless reblasted or used with a special tie coating. Field touch-up is always a problem.


All AC-Coatings are single component with no mixing, measuring or catalyzation and therefore have no pot life limitation.

Plural components must be precisely mixed. Pot life can be very short.


AC-Tar and AC-Zinc have excellent urethane flexibility, weatherability and abrasion resistance.

Epoxy tars are notoriously brittle and never as good as urethane for weathering and abrasion resistance.


AC-Tar is resistant to 800C continuous water immersion and intermittent temperatures up to 1150C.

Epoxy tars blister with exposure to intermittent temperatures over 760C.


AC-Zinc/AC-Tar cannot undercut. Typical salt spray resistances over 20,000 hours. This system does not require holiday testing.

Epoxy tar will undercut at mechanical damage or holiday, Epoxy tar requires holiday testing.


AC-Tar adheres to damp or green concrete. The concrete does not have to cure for 28 days.

Epoxy tar requires very dry concrete with a concrete with a concrete cure of a least 28 days. Recoating a water blasted surface is always a problem.


AC-Tar and AC-Zinc comply with all current and proposed VOC and lead reduction legislation.



AC-Tar does not irritate skin and eyes of the applicator. AC-Coatings are isocyanate monomer free. AC-Tar contains only 20-25% refined tar.

Epoxy tar is extremely irritating to applicators. Typical Epoxy tar contains up to 85% coal tar or refined tar.


AC-Tar contains micaceous iron oxide, which improves properties for abrasion, blistering, weathering, corrosion resistance & marine growth penetration.

Does not contain micaceous iron oxide.


AC-Zinc/AC-Tar has a dramatic advantage for miscellaneous damaged, abraded, or driven. (This system will not undercut or creep at mechanically damaged site. Undercutting is limited to less than 1/8 inch for 10 years in sail-water splash zone).

Epoxy tar will fail at every unrepaired damage point.


AC-Tar is always recommended at thinner films, 4-12 mils DFT.

Epoxy tar usually requires a minimum of 18 mils DFT.

TopUses Where AC Urethanes have Advantage

Bridges and Highways

Concrete and Wooden Floors

Marine and Harbour

Pulp, Paper and Sugar Industry

Production Plants & Equipments

Storage Tanks

Cross Country Pipelines

Power Generation Facilities

Water Works, Waste Water Pipelines

Petroleum and Fertilizer Industry

Pharmaceutical Industry

Effluent Treatment Plants

Amusements Parks