VCCA Home Forums TECHNICAL - GENERAL Body - Sheet Metal, Paint & Wood Painting frames and suspension parts Part 4

POR-15 advertises itself as, "a rust preventative paint designed for application directly on rusted or seasoned metal surfaces. It dries to a rock-hard, nonporous finish that won’t chip, crack, or peal: and it prevents rust from reoccurring by protecting metal from further exposure to moisture. POR-15 is sensitive to UV light (sun) and must be top-coated before prolonged exposure to sunlight. POR-15 is cured and strengthened by exposure to moisture and will dry faster under extreme humidity, but moderate to dry atmospheric conditions are most desirable when applying this product." Quote from instruction sheet.

You can purchase this product in a starter kit for around $25, a quart for $40. The starter kit contains gloves, brushes, a surface cleaner, a metal prep, and 4 ounces of POR-15. The paint is available in gloss or semi gloss black, silver, gray, and, clear. There are a host of complimentary products like self etching primers, epoxy putty, engine paints, high temperature manifold paints, top coats, and kits to repair gas tanks, floor pans, and trunks. Do some internet research, or request a brochure, to get a good idea of what you are getting into. I would start with a starter kit. You will also have to use the internet to find a dealer, or try ebay or Amazon.

All of the above is accurately explained but the devil is in the detail. Those who do not deal well with details will find all its idiosyncrasies not worth the effort. Let’s go through some of them. POR-15 needs a surface with some tooth to it or it peels off. Smooth or shiny surfaces do not work for good adhesion. For these surfaces they recommend a paint prep product to give the metal some tooth. I use POR-15 only on parts I have sandblasted or have a rusty surface.

Once the can is open, the paint begins to set up or thicken within about 15 minutes. So as you apply it, it gets thicker. They recommend that you take out of the can only what you can use in a short time, and under no circumstances return unused paint to the can or leave the can open. When replacing the lid on the can, make sure both the can and lid surfaces are completely free of any of the paint. I wipe both surfaces with lacquer thinner and put a piece of a plastic baggy between the surfaces to make sure I can get the lid off. Many cans of POR-15 become wasted by the lids bonding themselves to the can or the paint hardening in the can by improper storage. Once a can has been opened, it must be stored in a refrigerator until it is needed. When I buy a quart, I transfer it all to small 4 ounce cans, and then to the refrigerator. I can deal with wasting part of a 4 ounce can, but a $40 quart going bad would make me very unhappy. Remember how sensitive it is to humidity and temperature. Y’all in the south need to be especially careful.

Other problems arise as you apply the paint. It runs easily on vertical surfaces. You cannot go back to touch up an area because it starts getting tacky within minutes. It always seems that no matter how careful you are, you miss very small areas. You may find yourself thinking, "How could I have missed that 1/8th of an inch area? Or why doesn’t the paint job flow consistently so all coverage has the same sheen?" I have not applied it by spraying so only know that brushing it on will never meet show quality expectations. You get more brush marks as it sets up, and temperature and humidity always make it hard to predict if today it will apply as well as yesterday. I thin the paint with a few drops of lacquer thinner to try to maintain a consistent thickness. To apply a second coat, you must do it while the paint is still tacky, usually within an hour or less; if not, you have to sand the surface lightly to give the paint a tooth to stick to after it is completely cured. Remember that 1/8 of an inch spot you missed? Go ahead and touch it up, but in doing so you now have an area that does not match the sheen or smoothness of the rest.

You must wear gloves as you paint and clothes that you don’t care if they get paint on them. Paint on your skin will take at least 4 days to wear off unless you are willing to rub your skin repeatedly with lacquer thinner. As I have mentioned before, dealing with paint ventilation is a must, you do not want to be breathing in the vapors. You will find that the paint will take several hours before its vapors subside during the curing process. In that time every speck of dust seems to settle in the paint.

The good news about the surface sheen is that taking an oily rag and wiping the cured surface leaves a glossy sheen that seems to blend the paint well. Kind of like Armoral does on your dash or tires. Of course,this also attracts fine dust under normal driving conditions.

I do not like using their bushes or other cheap ones. They drop bristles easily and you spend a lot of time picking them out of your paint job. Unfortunately, brush cleanup is another problem. The paint sets up fast, so I first take a rag and squeeze out all the paint in the brush. Then I clean the brush in lacquer thinner, and squeeze out the lacquer thinner, and repeat the process until I have about 95% of the POR-15 out of the brush. Then I wash the brush out with cheap hair shampoo, and hang it to dry. A lot of work to reuse a brush!

A lot of my concerns are covered in literature sold with the product, but you have to be willing to do the reading and follow the directions. Assuming, can cost you a lot of money and frustration.

So why use the stuff and where should I use it? I use it because it does permanently encapsulate and waterproof rust prone areas on my car with a very durable finish. I use it for inside the bottom of doors, trunks, interior body panels, manifolds, on battery mounts, all suspension parts, cases of generators and starters, oil ventilation tubes, muffler hangers, brake parts, bolts, nuts, and clips. Remember anything small enough to fit in my 42" sandblast cabinet was blasted, first.

For bolts I paint the threads first, wipe 80% of the paint off with a rag, then paint the shaft and bolt head. I don’t paint the inside threads on a nut. That I use Anti-Seize in very small amounts. I am constantly taking parts on and off my car/engine and the paint does really holds up well. If I am worried about two surfaces scratching/rubbing when attaching them, like my shocks to the cross member, I make up thin plastic washers from milk bottle thickness plastic. This eliminates the chafing of metal on metal that I know will occur as I take parts off multiple times, and tighten them down.

POR-15 has great adhesion in areas that chemicals can be spilled. You feel like you are really preserving your car for the next generation, and after all your hard work cleaning an area, why not put a permanent preservative over it? Go ahead put it on where ever sun light won’t discolor it, but don’t think when you crawl under your car, you will see a perfect paint job. I don’t even think that should be one of its purposes?

It has great leveling properties, so it fills in deep rust pits and pin holes if you put tape on the opposite side of a panel, but not on a vertical surface. The silver color is manufactured to be thicker for filling in pits and floor repair work. Enough said for now. I am sure others will want to add their comments.

Good luck, Mike

P.S. I do appreciate the comments of others as we share best practices for maintaining our frames and suspension parts.

Great series Mike, this thread should be very helpful for those doing frames and suspension parts going forward. I use POR for many of the same items, and as advertised, it is virtually indestructible and has fairly good appearance with a little care during application. So much for the product endorsement, now a couple comments.

I never take the lid off a POR can. I use an awl to punch two holes, 180 degrees apart, through the single thickness of the lid near the outer edge and pour the amount I am going to use in a paper cup. I reseal the two holes with # 8 hex head screws which can be easily removed for the next usage. I have had cans sealed this way last for longer than a year with no waste.

Secondly, when using black I always use gloss rather than semi- gloss, it just seems to flow better with fewer brush marks. Within a day or so of it being dry, I always topcoat it with a conventional black primer. If it's a small part, I use a rattle can, for something larger a two part primer in a spray gun. The primer acts in the same manner as POR's advertised tie coat and allows me to top coat the item at any time in the future without fear of adhesion problems.

Regards, Mike

I use the same hole and screw method to remove Por 15 from the can. It works

Since I only use an ounce or less at a time, I only use a single hex-head screw. Squeeze the can when upside down into a lid from a discarded rattle paint can. That lid being slick plastic can be reused numerous times. I have used four quarts over a 10+ year period. Formally put the cans in a refrigerator but for the past several years have not even done that. The can I am presently working on is at least 2 years since I started using paint from. I live in one of the most humid areas of the USA. I only use the high gloss and find that a fine bristle brush is best. It does not leave any discernible brush strokes. I have used the same brush for several years. Clean the brush religiously with several washings in lacquer thinner.

When used properly POR 15 is a great product. Just don't put it anywhere you don't want it to be forever. It can be removed but takes herculean effort.

Thanks guys for the excellent feedback. I have always used the semi gloss and the silver and both require stirring. How do you get around not stirring the product? I do like your idea about just punching holes in the lid. That sure eliminates the mess of pouring from the can, or as I do using a small measuring spoon to dip out what I need. I also find the product best used on small parts where it smooths out well. Painting the bottom of my car is where I noticed it setting up so fast that I got the irregular sheen and some brush marks. I think that may be the nature of semi gloss paint when it is not stirred regularly and kept consistently thin.

I really can not see myself not having some always around. Thanks, Mike

The semi-gloss is a high gloss with flattening agent. Corn starch is one flattening agent. Don't know if that is what they use or not. If you shake the can well (yes I know they tell not to shake on the label) and then take the amount you need all will be well. Thinning will also accelerate the settling of the flattening agent so stirring often is necessary. I think it is far better to coat with the gloss and then a thin top coat of a semi-gloss from rattle can than use the semi-gloss straight.