Tutorial for POR-15 and Bedliner Coating of Sliders

The following is my procedure for applying POR-15 and bedliner to raw steel sliders. I thought I would provide full details on each step and some tips that might cause less aggravation for others who are thinking of going this route, as I couldn’t find all this information in one spot online.

Before I start going through the process in detail, I’ll note that it is unlikely that you will save either time or money by going this route over that of a $150 powder coating. Between paint, prep chemicals and sand paper, I am pretty sure I spent that much just on supplies. The total time spent prepping, sanding, painting and waiting for paint to tack/dry was on the order of 20 hours and took up most of two weekends to do.

Self-etching primer and rattle can paint will be the easiest/fastest/cheapest option, and if you live in an area where you can wheel frequently, and don’t have to deal with a lot of salt, it might be the best option as it will be easier to touch up repeatedly. On the other hand, POR-15 will hold up better to rock chips and salt than primer/paint, and given the frequency my sliders will see these conditions over that of banging them off rocks, I felt it was the better option (especially as I didn’t feel time and money were my primary concerns). The POR-15 option will still be far easier to touch up over that of powder coat too.

I apologize in advance for not having any photos to add to each step. To be honest, I felt like I was under a time crunch most of the time, and the last thing on my mind was taking pictures. I have provided photos of the finished product at the end, as well as photos of the sliders after being used in Moab.

So that all said, here goes:

1. Assuming you are starting with bare steel with some mill scale and oil on them, you need to degrease and clean the metal before sanding or grinding on it by using POR’s cleaner/degreaser . Otherwise, the contaminants can get embedded in the metal while sanding/grinding.

2. The POR cleaner/degreaser smells like windex and is likely essentially the same thing. It will not remove contaminates just by spraying it on. After applying, you still need to scrub the metal really good with a sponge/rag/scotchbrite pad before rinsing things off. I would recommend rinsing and repeating the cleaning process until running a clean paper towel over the metal comes out white. This is a messy process and if you are doing it indoors, make sure to have enough plastic up and round the area that will direct the water you are using to rinse off the slider into a floor drain. You don't need to wear a respirator or gloves with the cleaner (regardless of what the warning labels say), just don't snort it, ingest it or spray it in your eyes and you will be fine. However, I would suggest wearing gloves through the whole process to prevent adding body oil to the metal after it has been cleaned. It ended up taking 10 oz. of cleaner mixed 4(water):1(cleaner) to do both this step and step 5 below. I would recommend going to the hardware store and get a high output spray bottle to mix the cleaner and water in and use for application.

3. Once the metal is fully clean, you will need to sand off rust, mill scale, etc. with 80 to 120 grit sandpaper and get down to bare metal as best as possible. I would suggest 80 grit to give the POR more to bond to, and make the process go faster. You don't have to get every spec of rust, as the next metal prep step will take care of any small amounts of rust left behind. Once everything is sanded down, scrub everything off with the cleaner degreaser again until a paper towel stays white.

4. Then apply metal prep. A spray head attachment should come with the bottle, such that you can spray this solution straight from the bottle (you don’t dilute it down with water). If you don’t have a spray head attachment, just buy a second chemical resistant high output spray bottle from the hardware store. For this this step to turn out well, the temp needs to be above 60F for the conversion process to work in a relatively quick manner. The instructions state to keep the metal wet for 20 to 30 minutes, to allow the rust to be neutralize, etch the metal and leave a zinc oxide coating behind. I found that the zinc oxide coating left behind was not uniform. It seemed to form on parts of the steel that were less well sanded. It also seemed to not form if the metal was submerged in the liquid, such that it appears that oxygen needs to get to the metal as well, while the metal stays wet, to allow the zinc oxide to form. As such, I think it is beneficial to let the metal get slightly dry (damp to touch, not bone dry) periodically while spraying it down, to get the oxide to form better. Where the grey zinc oxide did not form, the steel changed to a golden color that could have been some sort of oxide or could have been light flash rust. Since POR will adhere well to light rust, I don't think flash rust is an issue. I ended up using the full quart of metal prep for both sliders. I could have probably conserved this some if I wasn't constantly spraying everything down and keeping it completely wet for the 30 minutes. I would recommend wearing a respirator and gloves during this step, as there are some fumes that are given off, and it wouldn’t surprise me if the solution is caustic.

5. After 20 to 30 minutes of spraying things down, the instructions indicate that you should rinse the metal off with water. I would consider letting the metal dry slightly before doing this to try to promote more zinc oxidation. Once you do rinse it off, make sure to scrub the metal a bit with a clean rag/sponge while running water over it. If you just run water over it without light scrubbing, once the metal dries, a thin layer of powdery zinc/rust will be left on the metal. I didn't scrub, just rinsed with water, and after everything was dry, ended up using dry paper towels to wipe off the excess of the powdery residue prior to applying the POR. It should be noted that I did end up painting one section of my sliders which did not have the powdery residue wiped off in advance, and the POR still bonded well. I would recommend rinsing with hot water and using a hair dryer to dry the metal as quickly as possible to limit flash rusting. As mentioned above, wear gloves to avoid contaminating the metal with body oil. Do not blow off the excess water with an air compressor as there can be a small amount of oil that is imparted to the part you just spent a bunch of time cleaning. POR-15 will not adhere to metal with oil on it.

6. Wait 12 to 24 hours after doing the metal prep step to make sure the metal is bone dry before applying POR. One 4 oz can of POR will result in two coats on one slider, so two to three 4-oz. cans should be all you need for sliders. The instructions indicate to stir not shake the material, and I can only assume this is to keep bubble formation down. I ended up shaking for the first application and then stirred for subsequent applications. I didn't really notice any difference in the final product, but I suppose stirring is safer. The paint is very thin when the can is first opened, but by the time I got to the bottom of the can, it had started to thicken up and become more difficult to spread out. As such, even if you get bigger cans of it, I would not pour out more than 3 to 4 oz. at a time. They say to apply the first coat thin, and I would agree this is prudent, as it will run and puddle if you slop it on. I would suggest working from the top down, and let gravity help you spread the paint on. You will definitely need a respirator and gloves, wear clothing that you don’t mind ruining, and put down plastic/cardboard on anything you don’t want paint on. You can thin and clean up non-cured POR with lacquer thinner, if necessary.

7. Once fully applied, depending on humidity, you will need to wait 3 to 6 hours for the paint to tack up before applying the second coat. It is recommended to apply the second coat before the first coat completely cures. The instructions say that you are ready for the second coat when dragging your finger across the paint results in some drag, but I find that a bit ambiguous. I would recommend adding the second coat somewhere between A) touching the paint doesn’t result is paint coming off on your glove but leaves an impression in the paint to B) touching the paint doesn’t leave an impression in the paint but it is still tacky. I would recommend painting a sacrificial swatch at the same time, and use that for testing the paint so that you are not leaving finger marks on the sliders.

8. Since the paint is glossy when dry, it can be difficult determining what you painted and didn’t paint when applying the second coat. You have to be methodical on the second coat. You can apply a third coat, and if you have time, it would be recommended as the paint does dry pretty thin. If you are planning on sanding the POR before applying the top coat (see below for further detail) I would highly recommend a third coat. I would however suggest that for each coat applied, that at the end of painting the whole part, go back to any sharp edges/corners/welds, and slop on a bit more paint. Since the paint has low viscosity, it will be pretty thin at these areas upon first application.

9. Since POR is not UV resistant, you will need to top coat it with something that is. I ended up using bedliner, but any paint works. There is also the POR top coat product, but from what I read, it is difficult to get it to apply evenly without runs unless you use the spray can version. There are three ways to go about top coating POR: 1) spray a dusting (just enough to completely take off the shine, but not enough to end up with wet paint sheen) of your top coat of choice on the POR 45 to 90 minutes after applying the last coat of POR and then let the POR continue to cure for at least 24 hours, 2) let the POR cure and then apply their Tie-Coat primer, 3) let the POR cure and then completely scuff with 320 grit. It is my understanding the best bonding is in the order I have listed. If you do decide to sand, even with 320 grit, you will likely completely sand through the POR on the edges/corners/welds. If you go this route, use a primer/top coat that that can be applied direct to metal such as bedliner. I would not use a self-etching primer such as Rustoleum, SEM, etc., as the etching compound in the primer might harm the POR.

10. I went with Option 1 on one slider and applied a coat of matte enamel spray paint about 90 minutes after applying the second coat of POR. At that point, the POR was still wet enough that it would just slightly come off on gloves when touching it. The key is to just dust enough to make the surface fully matte in finish (assuming you are using a matte primer/top coat). Once the dust coat is dry, the paint should be dry enough to touch and move the part. If you add too much top coat, the paint will crinkle when the POR cures and shrinks. If you using bedliner from a spray can, make sure you practice applying it on a sacrificial piece of substrate first, as that stuff can come out fast and be very uneven and go on too heavy if you spray too close to the part. Read the back of the can for offset distance and then trial and error it from there. After the POR/top coat dusting fully cures, wipe everything down with a wet or dry cloth towels to get rid of any loose top coat paint that didn’t fully adhere to the POR, before applying the next coat of top coat. You could also try light wet sanding areas that still appear shiny, but be careful about not getting too aggressive here and end up sanding through all the paint you applied.

11. I went with Option 3 on the other slider. Once the POR is fully cured, you can sand as needed to remove drip marks, etc. and then apply top coat. I did end up accidentally sanding down to metal on some welds and edges, and it only took one to two passes with the sand paper to get there, so be careful. I was wet sanding with 320 grit, and would not go more aggressive than that on the grit size.

12. If you are planning on using spray can bedliner as top coat, as mentioned above, practice on a sacrificial part first to get your technique down. I ended up using the professional Rustoleum bedliner in a can. Once I got my technique down, it resulted in a very even and good looking finish. However, I had to hold the spray can at least 18 inches from the part, so most of the paint coming out of the can wasn’t hitting the slider. This resulted in one can of paint being used for one coat of paint on each slider for a total of 4 cans and two coats. Given the wastefulness, if I had to do it over, I would have got bedliner in a regular paint can and spread it on with a roller or brush.

I'll sum up by saying this was a lot more work than I realized going in, but given how well the paint has held up so far with use, I am glad I went this route.

 

Here are pictures of the finished product. If you look closely enough as the second photo, you will notice the inside of the mounting plates are shiny. I did not add bedliner to the insides of the plates.

 

Photos of some of the scrapes I put on the sliders while doing Fins and Things, and taking a bad line to miss a mountain biker on White Rim. It is interesting to note that the bedliner will peel off the POR-15 easier than the POR-15 will peel of the steel, such that the bedliner acts like a sacrificial coat when dragging the sliders over rocks, thereby allowing the POR-15 to stay on the slider. However, the bedliner still is firmly enough attached to the POR-15, that using the slider as a step for the last 6 months has not caused any of the bedliner to delaminate from the POR-15 where I step on it. Very happy with how this has worked out.

 

I thought I would post an update on this as we are entering salt season. The sliders have been through one full upper midwest winter now (now entering their second), and there is no signs of rusting anywhere on the sliders. I did cover up the scraps shown in my previous post with Rustoleum bed liner and a paint brush. I have to say repainting with bed liner blends in really well with the original finish, but my sliders are usually dusty/dirty, so there may be some masking going on.

The bed liner is starting to wear off the top of the driver side slider below the front door as shown below (sorry for the dirt, I don't wash my truck unless it sees heavy mud or salt). I do use the slider as a step getting in and out of my vehicle about 50% of the time, so it does see a lot of abrasion. The bedliner on top of the sliders at the other three door locations is still fully intact. I haven't seen the POR start to oxidize in sunlight in these areas where bedliner has worn away, but I also park in a garage at home, and under a bridge at work, so that might be part of it. I also think I used the dusting the tacky POR with enamel paint technique on this side, so the enamel paint might still be protecting the POR from UV. At some point, I'll add another coat of bedliner to the top and that should remedy the issue.

FYI, don't use brake cleaner or alcohol to clean the slider before adding a new coat of bedliner, as those materials will cause the existing bedliner to soften up. Just use soap and water and wait for the sliders to dry.

 

Thanks for the great write-up! I'm debating how I want to paint my new sliders and this is very helpful. Any updates how your paint is holding up after an additional winter/salt season?

 

The bedliner did wear off a bit more on the driver side top since I posted the last photo. The POR is still intact, and I ended up applying a new coat of bed liner. That's holding up.

I did manage to scrap all the way through the POR while using the slider to pivot around a boulder on my last trip to Colorado. Put some bed liner on the scrapes, and all looks good. Still no rust to see anywhere on the slider so far. The original bed liner has held up pretty good to gravel spray over all.

 

Awesome thanks for the update! Planning to use nearly the same method and there are so many choices available. This one seems like the best combination for salt resistance and ease of maintenance/touch-up versus cost/difficulty of things like powdercoating.