POR-15 Spraying Question (for the paint experts)

[scottmcwms]

I am going to spray the underside of my tub with POR-15. I have everything ready (cleaned, metal ready, etc...) for the POR-15 coat. I have a touch-up paint sprayer that came with my air compressor. I am planning on using it to expedite the process. I'm not concerned that it isn't a high-quality paint sprayer as I don't really care about the appearance of the underside. I just want to get it done.

There are two sprayer tip options. An internal-mix tip and an external-mix tip. The external-mix tip says it is for medium bodied quick setting paints and the internal-mix tip says it is for heavy bodied slower setting paints. Which one should I use???

My second question is what do I need to use to clean the paint sprayer after use? I don't want the POR-15 to harden in the metallic paint sprayer passages, tip, and paint reservoir. Is Xylene the preferred method?

Thanks for your input.

Scott

 

[Bronco Wild]

Use POR's Solvent, it's the only thing from my experience that will really clean it up well. Be fast, if it drys at all, you're up the crick. And because you are spraying, the mist will dry instantly. The solvent will need to be used to spray, you won't be able to spray effectively without thinning it. Cover yourself and the surroundings well. It will be permanant on anything it lands on.

 

[dpmerrill]

If you have both nozzles, grab a scrap piece of metal and try both tips. It'll be worth the extra trouble since it will also let you adjust your gun so you don't spray too heavy.

I'm guessing your heavy bodied tip will work the best...

Don't forget to ventilate and as mentioned, cover yourself up. Not only is it nearly permanent, it's very toxic.

 

[allenfahey]

You will need to thin it about 10% with the POR reducer. When I spray it I use a 1.3 tip. Is there a size on the cap? It's a cheap gun so it might not have a size on it. Use the smaller one first at 10% reduction. A smaller tip will put on less material and less chance of runs and better atomization. After it gets tacky (1-2 hours) put on another coat. You want to put it on in thin coats.

Is the gun a gravity fed gun or siphon fed? If it's a gravity fed gun you might want to check out 3M's Paint Preperation System. It will allow you to literally spray upside down. It uses a bag inside a special cup much like an old baby bottle. Since you are spraying the underside of the tub a regular gun will often stop spraying.

For cleaning just use laquer thinner and where gloves and a resperator. And remember don't get it on your hootus

 

[scottmcwms]

Well, I sprayed the underneath with POR-15 this weekend. I really like the way it turned out. It took about 10-15 minutes to put on each coat. I think I would have spent at least 1 hours to paint each coat on. Spraying is the way to go!

Here are the results and my process. I used the external mix tip and it seems to work fine. I wasn't really worried about the appearance of the paint as it is the underside of the tub. All I really cared about was covering everything with a good protective layer.

I didn't use any thinner and it sprayed just fine. A thinner would have helped make it smoother, but once again I wasn't worried about the appearance. I was more concerned with getting the POR-15 too thin and it floating off and getting on everything but the tub. It was very windy this weekend (20-35 mph winds) and I didn't have any troubles keeping the POR-15 from drifting. I used about 40 psi from the compressor. I would suggest using a thinner if it were a surface that required a smooth finish.

I found that lacquer thinner was great at cleaning up the POR-15 overspray and also for cleaning up spills and my spray gun. Granted it was cold and dry this weekend and the POR-15 took a while to setup.

I found out that cold and dry is definitely not the best setup for curing POR-15. When I painted my frame back in September it took about 45 minutes for the POR-15 to cure enough for a second coat. It was about 85 degrees with 70% humidity. This weekend the first coat took almost 6 hours to get tacky. It was 40 degrees with 25% humidity. Needless to say, it will cure at those temps, but definitely not the most efficient way.

Scott

 

[eds66bronco]

how much paint did you need to do the 2 coats? i will be doing a tub this spring and need to figure out how much to get.

 

[Baja71]

You missed a spot. ;D ;D ;D

 

[scottmcwms]

2 quarts for the bottom and firewall of the tub. I put it on pretty thick. If I painted it on it would take probably 1.5 quarts. It will probably take another 1.5 quarts for the outer fenders, inner fenders, core support, underneath of the hood, and grill.

I bought 6 quarts and I think it will be enough to paint all these items:
Grill - front and back
Core Support - front and back
Inner Fenders and Wheel Tubs - all sides
Outer Front Fenders - inside
Tub - underside, wheel tubs, outer fenders, and firewall
Hood - underside
Tailgate - all sides
Doors - inside the cavity
Frame
Axle Housings
Driveshafts

Hope this helps.

Scott

 

[scottmcwms]

You missed a spot. ;D ;D ;D

Thanks Baja!!!

 

[Baja71]

Thanks Baja!!!

Heh! Sorry.

My real question is how did you get your tub in that position, and how are you going back level?

 

[scottmcwms]

Heh! Sorry.

My real question is how did you get your tub in that position, and how are you going back level?

I'm just messin' with you.

Well I built that sling (link here) and left off the side cross brace and horizontal supports. The tub was already on furniture dollies, so it wasn't far off the ground. I just put some carpet squares under the tub so that when I rolled it up on its side I would do any body damage from the concrete driveway. Then used a engine crane and a nylon sling to lift the body up on its side. Actually once you get it on its side it finds a happy spot and will sit there on its own. But don't trust it. Then I slid the sling around the body, put the tie-downs under it and cranked it up. Pretty simple. It only took me about 2 hours from the time I started building the sling to the time the body was up in it. To get it back level I will just go backward from here.

Scott

 

[eds66bronco]

2 quarts for the bottom and firewall of the tub. I put it on pretty thick. If I painted it on it would take probably 1.5 quarts. It will probably take another 1.5 quarts for the outer fenders, inner fenders, core support, underneath of the hood, and grill.

I bought 6 quarts and I think it will be enough to paint all these items:
Grill - front and back
Core Support - front and back
Inner Fenders and Wheel Tubs - all sides
Outer Front Fenders - inside
Tub - underside, wheel tubs, outer fenders, and firewall
Hood - underside
Tailgate - all sides
Doors - inside the cavity
Frame
Axle Housings
Driveshafts

Hope this helps.

Scott

thanks...
nice job by the way!

 

[1957]

Great job. To what extent did you prep the metal? Did you sandblast? wire brush? Was it 100% rust free. Is this POR15 the best to use for this application even with rust? Will be doing mine this summer time permitting don't know what direction to go in.

 

[ProjectCumminsBronco]

On your encounter with the POR-15 can you spray it over the whole body then still be able to lay down a nice paint job?

 

[allenfahey]

On your encounter with the POR-15 can you spray it over the whole body then still be able to lay down a nice paint job?

Yes, there are 2 ways to do it. One way is to spray it on then let it dry, sand with 220 or 320, red scuff it. Prime it with urethane primer, sand with 400-500 and paint. Another way is to spray the POR on then after it almost dries. When I say almost dry it needs to be barely tackey, you should hardley see your fingerprint in it. Spray your primer on but spray it very dry for 2 coats. If you rush it you will get nasty fisheyes all over. After the primer tacks off you can lay the primer on wet. I've done it the 2nd way before and turned out great but learned the hard way with the fisheyes

 

[ProjectCumminsBronco]

Yes, there are 2 ways to do it. One way is to spray it on then let it dry, sand with 220 or 320, red scuff it. Prime it with urethane primer, sand with 400-500 and paint. Another way is to spray the POR on then after it almost dries. When I say almost dry it needs to be barely tackey, you should hardley see your fingerprint in it. Spray your primer on but spray it very dry for 2 coats. If you rush it you will get nasty fisheyes all over. After the primer tacks off you can lay the primer on wet. I've done it the 2nd way before and turned out great but learned the hard way with the fisheyes

Cool thanks for the heads up. I had been thinking POR-15 under the whole underside and front clip and their insides.

The Tub inside will be bedliner.

But I also wanted to protect the outside were paint was going to be.

Again thanks for the info.

 

[scottmcwms]

Well, I don't have any experience with putting body paint over the POR-15. I haven't done that. All my applications have been in places where the POR-15 will be the last coat.

As for the preparation question, I stripped it down to the metal with aircraft stripper and a wire wheel on an angle grinder. All the rusted floor pans were replaced. If you look closely at the picture (I will attach another that shows this better) you will see that I didn't replace it with OEM replica floor pans. I don't really care that it looks completely stock. I used 18 gauge and 12 gauge sheetmetal for the floor pans. The bed and the floor pans under the front passenger's feet are made of the 12 gauge steel. Pretty beefy stuff that doesn't need any bracing. I also incorporated a storage unit under the driver's seat. It looks like a dropped floor from this picture, but the floorboard is normal on the other side (see the second picture). I will put more information out later as I haven't finished that yet.

Anyway I stripped it down to bare metal, replaced most of the rusty areas, used the POR-15 products called Marine Clean to degrease the area, and Metal Ready to etch the area, then painted.