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FAQs

Below you'll find commonly asked questions by our customers. Have a question not found below? Send us a message.

Rust is caused by moisture coming in contact with metal, which causes a chemical action called oxidation. All paints provide a measure of protection for a while, but since they are eventually softened and weakened by moisture, it is only a matter of time before moisture penetrates the painted surface and attacks the metal below. All of the so-called rust preventive paints on the market (except POR-15) are weakened by exposure to moisture. POR-15 is strengthened by exposure to moisture. Notice the hardness of the POR-15 coating. It doesn't chip, crack, or peel like ordinary paints do, and its hardness will resist the wear and tear of every day life.

Rust conversion products claim to change the chemical nature of rust and convert it to a more stable element that won't rust again. History of the failure of these products is well documented; most simply don't work for more than a few months at best, and they are subject to the same chipping and cracking that occurs with ordinary rust coatings.

POR-15 works because it chemically bonds to rusted metal and forms a rock- hard, non-porous coating that won't crack, chip, or peel. It keeps moisture away from metal with a coating that is strengthened by continued exposure to moisture.

Most people brush it on, but many spray also. Proper equipment and organic vapor particulate respirators for solvents are essential for spraying.


You should use only POR-15 Solvent for thinning. Keep lacquer thinner handy for clean-up. Do not thin POR-15 more than 5%.

Absolutely. POR-15 will accept all paints, including lacquer-based paints. POR-15 Tie-Coat Primer is the best prime coat to use before topcoating POR-15. Be sure to read thoroughly our directions and tip sheets regarding topcoating before using POR-15.

Yes. First paint both sides of the rusted area with POR-15; then use body filler or putty as soon as the POR-15 is dry to the touch.

That depends on the ambient humidity (surrounding area). The more humid the area, the faster the dry time, which usually varies from 3 to 6 hours.

No, but if you do, remove it at once with solvent or lacquer thinner. If POR-15 dries on your skin, nothing will take it off, and you will 'wear' it for 3 or 4 days until natural oils and flaking skin remove it.

Yes. That's why you must always paint in a well-ventilated area and keep your nose away from the paint container. POR-15 is not dangerous if you follow our simple directions.

POR-15 likes rusted surfaces best. Seasoned metal and sandblasted metal are also good. POR-15 does not adhere well to smooth, shiny surfaces, but will adhere well to those surfaces with the proper preparation.

We make a product called 'Metal-Ready'. It's a rust remover that leaves a zinc phosphate coating on base metal, the perfect preprimer for POR-15. NOTE: New steel is coated with a protective oil finish at the mill. This finish must be removed before using POR-15 or Metal-Ready. Clean metal first with POR-15 Marine-Clean, then rinse with water and dry.

Silver contains metal filler and should be used in badly rusted, pitted areas. It will fill in holes better than black or clear. Black is generally used on frames, underside of fenders, etc. because that's the usual color there. Clear renders the smoothest finish and is often used as a preprimer on exterior surfaces; Gray is great on concrete floors, bilges, storage areas, as well as steel.

No, but POR-15 has an ultra-violet sensitivity and must be topcoated if continually exposed to sunlight. Once topcoated, POR-15 will remain effective for many years.

If the surface is exposed to the sun for an extended amount of time, the UV rays will eventually break down the POR-15 and cause it to fail. That?s why we recommend you topcoat it.

Yes, but you will lose the important benefits of POR-15. You must remember that ordinary paints are weakened by exposure to moisture. POR-15 can't stop rust if it isn't in direct contact with the base metal.

Absolutely. POR-15 is fully compatible with fiberglass and can be used to repair cracks in gelcoat. It will adhere better than polyester resin and has greater strength. Use also with fiberglass cloth to make super-strong surfaces in rusted-out areas. But be aware that POR-15 doesn't contain styrene and thus cannot melt fiberglass cloth like polyester resin does.

First, wire brush loose rust and scale. Then remove any grease or oil with POR-15 MARINE=CLEAN and prep with POR-15 METAL-READY. DO NOT USE SOLVENT- BASED CLEANERS.

Use POR-15 Tie-Coat Primer after POR-15 is dry, following directions on can. Tie-Coat Primer may be sprayed or brushed in multiple coats if desired. Sands to a perfect finish.

CHROME MOULDING CLIPS can scratch a new paint job when they are pushed through the body. POR-15, even if scratched off, will only rust where it's removed, so rust won't travel upward to ruin that new paint job. Coat around holes and under chrome before you prime and paint.

ROOF DRIP RAILS are a place where rust begins early. Put on a coat of POR-15 and let dry. Then apply a second coat, wait for it to dry, then apply a coat of POR-15Tie-Coat Primer and topcoat as desired.

STAINLESS STEEL TRIM PIECES that push down around the windshield... if they won't stay down, put some POR-15 in the channel and brace it with wood strips overnight. Regarding windshields, with the rubber removed, put a coat of POR-15 around the body where the rubber rests; this is a high humidity area and should be sealed with POR-15POR-15 INSIDE REAR EXHAUSTS will stop rust where it starts.

LOWER COWL SECTIONS, ROCKER PANELS, LOWER PORTION OF FENDERS AND REAR QUARTERS, INSIDE DOORS are other good places to coat with POR-15.

Put a piece of tape behind the larger pinholes, then paint. When the paint dries, pull the tape off and paint the back side as well. POR-15 can be used to seal gas tanks, also, and POR-15 PUTTY will take care of larger holes.

OLD CARDBOARD INTERIOR PIECES AND MOLDED VINYL VISORS can be coated with POR-15 and then painted over with vinyl dye.

Reminder: POR-15 SHOULD BE STIRRED, not shaken, each time you use it.

All estimates below are made using one coat on the area being treated; however, we recommend two coats in most applications.

POR-15 application on non porous surfaces (most metals):
Approximate coverage:

Pint = 50 sq. ft.Quart = 96 sq. ft.Gallon = 350 sq. ft.

For porous surfaces like wood & concrete, coverage will be about 20% less.
When painting on metal surfaces, we recommend at least 20oz. of Metal Ready for every quart of paint or coating you use

Marine Clean is mixed with water; ratios will vary depending on application.
(Hot water will increase effectiveness)

Engine Enamels: One pint will cover any standard automobile engine block

Hi-Temperature Paints (Factory Manifold Grey, Black Velvet, POR-20): For exhaust components 8oz. will coat an average set of manifolds and a small set of headers.

Super Starter Kit: (Great for testing & smaller projects): 12 sq. ft.

Floor pan and Trunk Kit: Enough products to do two floor pans or one entire trunk

Auto Fuel Tank Repair Kit: Seals up to a 25 Gal. tank

Motorcycle / Utility Fuel Tank Repair Kit: Seals up to a 6 Gal. tank

Weatherometer - The weatherometer is perhaps the most accurate weather resistance indicator due to the cycling of conditions. The cycle is 30 mins sun at 135 degrees F, 30% relative humidity and 30 mins dark at 75-80 degrees F, 100% relative humidity1,000 hours of exposure equals 5 years of simulated exposure in the Rocky Mountain region. There was no change in 3 panels coated with POR-15 exposed for 2,000 hours.

ASTM B-117 Salt Spray - The oldest and most wildly used weather cabinet test. It introduces a spray in a closed chamber where specimens are exposed at specific locations and angles. It creates a 100% relative humidity condition in the exposure zone.

Two separate B-117 tests. One with new steel and the other with rusted steel.

No change in 3 panels of new steel exposed for 250 hours at 98 degrees. Thickness = 2 milsNo change in 3 panels of rusted steel exposed for 1000 hours at 98 degrees. Thickness = 2 mils

ASTM C-580 Flexural Strength - This test method measure flexural strength and modulus of elasticity expressed in pounds per square inch.

5,200 pounds per square inch

ASTM C-579 Compressive Strength - This test method measures compressive strength, the capacity of a material to withstand axially directed pushing forces.

12,500 pounds per square inch - Verified. Not tested to failure.

ASTM C-307 Tensile Strength - This test measures tensile strength of cured chemical-resistant materials..

3,200 pounds per square inch

ASTM D-4541 Bond Strength To Concrete - This test method measures the strength of a coatings bond to concrete.

Concrete fails before POR-15. It far exceeds the tensile strength of concrete

ASTM C-501 Taber Abraser - This industry standard for the establishment of an abrasive wear by determination of the loss of weight resulting from abrasion.

In two separate ASTM C-501 Taber Abraser tests, POR-15 had:

No loss after 1,000 cycles with a 1,000 gram abraser

Loss after 10,000 cycles with 1,000 gram abraser = 0.09 grams

Chemical Bath Test

After 200 hours of soaking in the following chemical bathes, panels coated with POR-15 experienced no changes: 10% hydrochloric acid, 50% sulphuric acid, 55% chromate, 85% phosphoric acid, 10% sodium hydroxide 98% methanol

Raw Sewage Test

A metal box that houses a filter for raw sewage in a treatment facility was coated with POR-15. After a year of service no viable undercutting or rusting was present on the housing.

Mil-D-3134J Impact Resistance

POR-15 exceeds standards in paragraph 3.15

ASTM C-413 Water Absorption - This test method covers the determination of the absorption of chemical-resistant mortars, grouts, monolithic surfacings, and polymer concretes.

0.0001 maximum

NACE Stand TM0174

0.00 POR-15 is a non-porous coating

Temperature Resistance

POR-15 is temperature resistant up to 450 degrees. A test showed that no adhesion was lost at 450 degrees F for 10 hours