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Q: Many Products Claim To Stop Rust; Some Are Paints, Some Are Conversion Products, Some Are Rust Treatments. None Seem To Really Stop Rust Permanently. Why Is POR-15 Different, And Why Should I Believe It Will Work Any Better?

A: 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 POR15) 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.

Q: Is It Better To Brush Or Spray Por-15?

A: Most people brush it on, but many spray also (using POR15 Solvent). Proper equipment and organic vapour particulate respirators for solvents are essential for spraying.

Q: How Do I Thin Por-15 If I Want To Spray It?

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

Q: Can I Paint Over Por-15 With Other Paints?

A: Yes you can, but just to be on the safe side, we would recommend you to test on a small sample first. POR-15 will accept other paints, including lacquer-based paints. POR15 High Build Primer (was Tie-Coat Primer) or POR15 Self Etch Primer is the best prime coat to use before top-coating POR15. Be sure to read thoroughly our directions and tip sheets regarding top-coating before using POR-15.

Q: Can I Use Body Filler Or Putty With Por-15?

A: 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.

Q: How Long Does It Take Por 15 To Dry?

A: That depends on the ambient humidity (surrounding area). The more humid the area, the faster the dry time.

Q: Is It Dangerous To Get Por 15 On My Hands?

A: No, but if you do, remove it at once with solvent or lacquer thinner. If POR15 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.

Q: Are The Por-15 Vapours Dangerous To My Health?

A: 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.

Q: What Is The Best Surface On Which To Paint Por-15?

A: 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.

Q: What Is The 'Proper Preparation'?

A: We make a product called 'Metal Prep' (was called Metal Ready or Prep & Ready). It's a rust remover that leaves a zinc phosphate coating on base metal, the perfect pre-primer 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 Cleaner Degreaser (was Marine-Clean), then rinse with water and dry.

Q: Which Por 15 (Black, Silver, Grey, Clear) Should I Use?

A: 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 colour there. Clear renders the smoothest finish and is often used as a pre-primer on exterior surfaces; Grey is great on concrete floors, bilges, storage areas, as well as steel.

Q: Must I Paint Over Por-15 To Make It Last?

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

Q: Will The Sun Destroy My Por-15 Coating If I Don't Topcoat It?

A: 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.

Q: Can I Apply Por-15 Over Other Paints?

A: 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.

Q: Can Por-15 Be Used With Fiberglass?

A: 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.

Mentioned Products:

- POR15 Cleaner Degreaser (was Marine Clean)

- POR15 Metal Prep (was Prep and Ready)

- POR15 Rust Preventive Paint

- POR15 Top Coat Paint

- POR Patch

- POR15 Power Mesh

2,005 Posts
Ive used this stuff and i must say it gives a very nice finish to suspension parts etc, however the bloody stuff does peel, i've tried it on all sorts, it only seems ok if you have no edge ie encased.

Welding Guru
791 Posts
A sales pitch with no real determining statements apart from use the stuff we sell. I have used Por 15 and could not guarantee it performs any better than the 68% phosphoric acid I use to try and prevent oxidation .
My motto is cut it out and replace with good metal.
My middle son works in a highly specialised corrosion laboratory and they long term test all kinds of materials against all kinds of corrosive environments and his colleagues recommend removing all laminated areas before applying any "rust converter" on very lightly corroded sections.
the biggest enemy to material integrity (this includes all stainless steels, is CHLORIDES) the concentration of which will enable the development of microscopic pits in the material surface within grain boundaries. if this is not washed out or diluted then concentrated acids will continue to develop and form deeper pits (what looks like a pinhole on the surface can migrate sub surface and cause voids that develop via end grain attack of the metal)
that is why we always use demineralised water on testing stainless steel vessels and pipework, as the chloride content of the test water can cause disruption to the passive layer present on treated stainless steel and will result in chloride pitting if not properly pickled and passivated.
if it can challenge stainless steel then carbon steel is even more subsceptible.
Think of it this way:
Countries that treat roads with salt are naturally increasing the chloride content of surface water and therefore rust issues prevail
Countries that don't use salt have almost zero major rust issues (that's why we all like cars from dry states as its normally only surface rust)
Cheers, Brendon

2,539 Posts
I coated my roadster inside and out in it , and all i will say is don't put body filler on it as it just lifts and peels , i ended up spending days just putting a blade under it and peeling it all off, and thats after using the metal prep as instructed....

134 Posts
just got the por-15 tank sealer do i need the other stuff or is just a good clean so there are no bits left loose?

156 Posts
I've used it . . But didn't like that I could lift it off the shot blasted metal with my finger nail .

Half a tin going free if any one wants some
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