• Home
  • POR 15 Vs Rust Encapsulator - Products Comparision Part 2

Rust Encapsulator Vs. POR-15

Which One Works Best on a Rusty Hood
(continued from Page 1)

Product Comparison by LARRY LYLES of Auto Restorer magazine

My Test Results

POR-15 - I found this product a little too thick to spray even when reduced by the recommended 5%. After experimenting on a test panel, I determined the best reduction was about 10% using POR-15 solvent as a reducing agent. Per the instructions, I applied two thin coats, allowing 10 to 15 minutes between coats for the product to flash. The gun was set to 30 psi at the inlet.

Even though I reduced the product until it reached what I determined to be a proper spraying consistency, I was still left with a slight orange peel effect on the surface.

The instructions stated POR-15 could be top coated after 3 to 6 hours of cure time. In this case cure time turned out to be closer to 12 hours. The product ceased to fingerprint after 10 hours. The instructions also stated the product could be top coated with polyester filler once it ceases to fingerprint, but should not be painted until it is fully cured.

Finally, POR-15 had a tendency to solvent pop. I could understand having this problem on the portion of the hood where I had applied two coats. However, I found just as many solvent pops on the portion of the hood that only had one coat.

I considered the possibility that I had over-reduced the product and brought on the solvent pop problem myself. To double-check the problem I applied a single coat to another panel (not shown) using a brush and the product at full strength (no thinner). The solvent pop problem persisted.

Now for the bad news. Check out the photo at the top center of the previous page. Despite having properly cleaned and prepped the entire top side of the hood per instructions, this nasty ring of lifted paint slowly began to appear on the POR-15 side. It took nearly two months before the ring reached this point.

The ring obviously resulted from leaving a can of something on the bare metal surface of the hood during its stay out behind the shop. The photo at the top right of the previous page shows another problem on the PRO-15 side of the hood. The product is beginning to lift along the line of rusted metal, indicating rust from the strip of bare metal is beginning to creep under the edge of the product, separating it from the panel.

Finally, in the photo at the top of this page, you can see exactly what the sun is doing to POR-15. The dark section near the upper right is an area I kept covered to keep the sunlight out.

What are all those lines appearing in the finish? Believe it or not, those are grinder marks left from the initial paint removal. The product (POR-15) appears to have gone through a small amount of shrinkage after the panel was sprayed.

Eastwood Rust Encapsulator - I don't mean to sound like an advertisement for this product, but Rust Encapsulator sprayed on without a flaw, cured within the time frame allowed (about 4 hours in this case), and laid level smooth. I could have painted over the product immediately upon curing and had a completely acceptable finish. I did thin the product 10% before spraying to bring it to the consistency of lacquer.

The product also stood up well along the line of rusted metal (as seen on the right side of the photo on the top right of the previous page). I detected absolutely no bubbling or rust infiltration under the product and it showed no sign of shrinkage over the grinder marks.

Some Observations

I have to give both products an "A" for sanding. I took a DA sander with 320-grit sandpaper to both and each one sanded quickly with no tendency to clog the paper.

If you decide to spray either of these products I suggest purchasing a cheap, throw-away gun so you don't end up (like I did) spending more than an hour cleaning the spray gun. Once you open the can of either product, use a plastic bag between the cap and the can to prevent the lid from becoming permanently attached to the can.


So which product worked the best? I have to say as a general rust preventative both products will do the job. However, as a restorer of old cars I have to be concerned with those minute areas of rust you can never seem to properly coat or cover. For that, I have to lean towards Rust Encapsulator because of its ability to prevent rust creep.

As far as application, I also have to lean towards Rust Encapsulator. Just clean the panel, wipe it with lacquer thinner to remove any remaining grease or grime, and apply the coating. On the other hand, POR-15 requires additional products to prep the panel. As you saw in the photo with the ring, even the slightest problem with cleaning will affect the overall job.

For topcoating, which as far as I'm concerned is a necessity, I have to give POR-15 a poor grade. While the problem of solvent popping may have been exclusive to me, I don't relish the idea of having to prime or seal every rust-protected chunk of my car just to get rid of the solvent pops. I'm also concerned with the apparent shrinkage the product demonstrated and the extended length of the time required for curing.

I have to give Rust Encapsulator an "A" for topcoating. Each coat went on smooth and laid down flat, even when brushed. I found no evidence of shrinkage on any test panel I coated and the product dried and cured within a reasonable length of time.

Finally I have to consider the cost. Rust Encapsulator costs less than POR-15 and especially so when you consider the extra expense of additional products required for using POR-15.

Reprinted with permission of Auto Restorer magazine. For subscription information call 888-333-0436 or visit autorestorermagazine.com