303 Over Penetrol?

Just finnished putting penetrol on a canoe hull to restore the color to the oxidized gelcoat. (Thanks N.T.!) Can 303 be used over the penetrol after it has had time to set up?

I did
use 303 over Marine Penetrol and my Wildfire looked very nice.

Set up time?
How long did you wait before putting on the 303? Hours? Days?

I thought I’d give it a few days.

The penetrol made a huge difference on the gelcoat, though I’m worried I may have left too much on at the surface.

Oh Man, Penetrol?
am I the only one here concerned with more oil based products being introduced into streams?

Interesting Subject
I’m certainly concerned with the environment. My understanding was that 303 stayed on what you applied it to and was recommended by most of the manufacturers. Of course that doesn’t make it so.

Penetrol seems like a varnish somewhat. My penetrol job got rained on (got to love those unexpected spot showers) about 45 minutes after application. The water, beaded, ran off and did not appear to interact with the finish. Flood is marketing a penetrol product specifically for marine use. I’m not sure if its the same exact formula. My guess is that it is and just put in a different can and charged more for at the Marine stores. Maybe an email to them is in order to ask about the environmental friendliness of their products.

If 303 washes off, is there an alternative for giving the boat some UV protection over the penetrol? Marine wax?

Wait time for 303
I did this last spring, and as I remember, I waited several days to put on the 303 over the Marine Penetrol. I did both inside a well lighted garage with the doors open, to reduce dirt/dust in air but maintain air circulation.

see my photos if you like:





Also, I’ve got to thank N.T. again for the Marine Penetrol suggestion.

Well, I went ahead and put a “protectant” over the penetrol. I used McNett UV Tech, which I forgot that I had. Can’t remember where I bought it actually, but it is supposed to have an “environmentally friendly” formula. I tested it on a spot and it seemed fine with the penetrol so I did the whole thing. It all seems very compatable, and feels like a wax finish very slick, and brand new looking.

I did additional cleaning on the vinyl gunnels today and had to rinse and wipe off some residual barkeepers friend off the hull, no problems. The boat is shaping up better than I’d hoped really. Its going to the inlaws if they want it, so its nice that it is looking this sharp.

Thanks BLK
That Wildfire cleaned up mighty nice. Sweet looking Peregrine you’ve got there too!

It is amazing
how well these boats clean up, without any special skills or knowledge beyond what I’ve picked up here on paddling.net.

I’ve used 303 as a UV barrier & polish for the past few years. Though I have noticed that it wears off fairly quickly it seems to me that it doesn’t all come off all at one time – in an instant – with exposure to water. I switched to 303 after it was revealed at this board that Armor-all was an environmental bummer. Are we now to conclude that 303 is a bummer as well? I certainly don’t like the fact that its environmental impact seems to be a secret… That sort of thing leaves me suspicious.

What’s the environmental impact of this Penetrol stuff??? I don’t know how to look that up – I’m not sure of the full manufacturer’s/product name and don’t know where to look. So what’s the deal with THIS stuff?

As an aside: I live in an area adjoining a vase watershed that has been seriously impacted by a DuPont Teflon/C8 plant. I hope this Penetrol stuff is not another Teflon/C8 based product…

“You don’t know what you got ‘till it’s gone”. - RK

Penetrol is an oil based paint additive, used to make alkyd paints flow and self level. It doesn’t thin the paint so much as “conditions” it. (Their words).

For a time I was a high steel painter at the Indy 500 and spent several summers out there painting the ironwork under the bleachers. We used Penetrol a lot.

The ONLY time we applied it as a barrier coat by itself was to some extremely rusted steel going through a tunnel, which ran under the bleachers but over the top of the restrooms. It was real shi–y work. The rust was so heavy it had to be beaten off with chipping hammers. After cleaning, we coated the beams with P’trol which had just a little red paint added. (So that we could tell “where we’d been”.) More to settle the dust than anything else.

After it “cured” (usually the next day) we pulled through with a primer coat of red and then a finish of gray. Our 10 man crew spent the whole summer in that tunnel, dragging lights, picks and walkboards. It was no fun.

Even though Penetrol sets up and forms a film it isn’t anything like varnish. I do not believe it fully cures and with time will be miscible in water.

I have coated wheelbarrow and garden tool handles with the stuff and even though it initially looks great within a year it’s gone. I would be very hesitant to coat a canoe with the stuff.

I think these are good questions.
Here is a link to the flood company’s web site. I emailed them yesterday asking specifically about penetrol possible washing off into the water and becoming a polutant/toxic etc. Looking at the MSDSs it looks like the “hazardous” content of penetrol, marine penetrol, and glassworks are exactly the same. There might be formulation differences of course. Maybe the marine and glassworks are formulated to reduce leaching into water. It would be great to get some clear answers.


Here is McNett UV Tech’s product page


I see…
I see the thread clipper has been busy…

More specific information
on marine penetrol


I think N.T. has gone to perform more
definitive experiments. I have some in mind also. I think it is critically important to find out how 303, McNett, and Armorall stand up to water, because if they are washing off in the first half mile of paddling, we are being cheated and should file a class action suit against the companies.

I think we >can< assume that paddlers saying they put 303 on “a couple of times a season” should reconsider.

Yes and I’ve come to the conclusion

– Last Updated: May-14-07 6:29 AM EST –

that people who think that 303 does not wash off are the exact same armchair experts that never put their boats in the water. In that case it will last a good long time. Also they never have to worry about refurbishing their boats because they never use them. I know a few of those types.

But you've got me thinking, It's going to be a nice day here, hot sunny. I think I will do a photo experiment by spraying some 303 on some poly plastic and let it set out in the sun all day. Later I'll put some water on it and photograph the results and show you what you can't seem to see (need new glasses?)LOL

I’ve been using it and yes, it washes off.

Does it pollute our waterways when it comes off?

Does it offer any real UV protection?

I use it for UV protection/scuff ‘camouflage’ on our ABS boats and as a polish on our composite boats. I’ve been maintaining a family fleet of canoes with 303 to the tune of about 2 quarts of the stuff a year. Yeah, I want UV protection for our much used boats (we paddle 50-60 days a year) and I like things looking “spiff”. But I don’t want to be the captain of the Exxon Valdese…

I think it’s time for some hard facts on this product. Many manufacturers recommend it – but is it useless for UV protection? …and even worse… is it an environmental bummer?

good morning Randal
Thank you for noticing that 303 washes off. It’s hard not to see that if you use it. For those who can’t admit that I’ve set up a little test. I sprayed an old poly coffee container lid and a plastic mirror with 303 and wiped off the excess. I’ll let that cook all day in the sun while I’m at work. Later I’ll add some water and we’ll see if it turns into the milky mess that I think it will.

Thanks again…Mr Wizard



Hey Norb
Good morning to you! I think you’ll need your pointy hat and the long flowing robe for the experiments – ya need to dress the part ya know! ;^)

Penetrol is a petroleum distillate mixture that includes “Stoddard solvent” and benzine. Though environmental testing hasn’t been extensive, some of the ingredients in Stoddards can cause cancer.

A link: http://tinyurl.com/243784

The chemical composition of Penetrol and Marine Penetrol are identical. It’s only the packaging and price that are different.

I’ll say it again, I would be very hesitant to treat a canoe with Penetrol.