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When Penetrol dries, it leaves a fairly thick film, which I generally don't want on a working metal surface. I once made the mistake of leaving wet Penetrol on an old 10ER arbor and nut that I had Evaporusted and then polished with Nyalox brushes. I let the Penetrol dry while they were assembled. It glued them together quite solidly!

Also, it can sometimes take pure Penetrol quite a long time to dry fully -- as in many days -- to the point that it's not sticky. If you clean it off the top surface of the metal while it's only partially dried, that solves both of these problems.

Penetrol is marketed primarily as a paint additive; rust-prevention is secondary. But Flood (the manufacturer/brand) used to publish a PDF with information on how to use it as a rust preventative, and an explanation of how it works. It assumed that you'd be painting over top of it (as in restoring a rusty iron gate), so there was no mention of taking off the surface layer. I couldn't find that PDF just now, but I did find a retail site for Penetrol Anti-Rust Spray that had a product description with a lot of the same verbiage:


The process that I recommended leaves the Penetrol down in the pits and crevices, where it prevents the formation of new rust by blocking moisture and oxygen. And it leaves the top of the metal surface clean, where you can lubricate and protect it with JPW.

Thanks Dennis. Yeah, I was just trying to understand if Penetrol should be left on top of the surface, or just down in any pits from past rust. Ideally you would want a thin coat of Penetrol, even on the high spots, right? Or is it a challenge because Penetrol dries to a sticky surface? I guess once I start using it, it will make more sense. I was just surprised by the need to go back over it with a solvent...that's all. Much appreciated.

RFGuy wrote: ↑Fri Aug 27, 2021 3:51 pm Thanks Dennis. Yeah, I was just trying to understand if Penetrol should be left on top of the surface, or just down in any pits from past rust. Ideally you would want a thin coat of Penetrol, even on the high spots, right? Or is it a challenge because Penetrol dries to a sticky surface? I guess once I start using it, it will make more sense. I was just surprised by the need to go back over it with a solvent...that's all. Much appreciated.

The surface layer that fully-dried Penetrol leaves is a lot like a layer of paint (except with no pigment). Generally, bare ferrous-metal surfaces on machines were left bare for a reason. To my way of thinking, if you wouldn't want the surface painted, you wouldn't want a layer of Penetrol on it either.

BuckeyeDennis wrote: ↑Fri Aug 27, 2021 6:57 pm The surface layer that fully-dried Penetrol leaves is a lot like a layer of paint (except with no pigment). Generally, bare ferrous-metal surfaces on machines were left bare for a reason. To my way of thinking, if you wouldn't want the surface painted, you wouldn't want a layer of Penetrol on it either.

Got it. Well, if the surface of cured Penetrol was smooth, I was thinking it would be okay but maybe it is better to leave it as close to bare metal as possible? My thinking on this is that I know some woodworkers choose to coat their cast iron surfaces (tablesaw, jointer, bandsaw, etc.) with a layer of polyurethane. I don't know how well this works, but I have heard of some having success with this, I believe. Anyway, I will follow-up your tips with Penetrol when I get some.

Scott does four segments on rust removal and protection with his jointer, and across these he discusses the use of quite a few products, including WD-40, Penetrol, polyurethane, evaporust, and others. He ends up setting up a test of different types of polyurethane as a protector, including a water-based version. (I’m curious to know what the test has shown him; I wonder if he’s come back to that in a later episode.) He says he likes to do a 50-50 mixture of polyurethane and mineral spirits, and put it on as a wash. I found this to be an interesting set of videos, you can find them at the link below, scroll down about half way.

viewtopic.php?f=7&t=23920&start=80#top

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It is the 'depths' of the pits that the penetrol is applied for. Removing the surface application hopefully leaves it in thar.

The JPW is the anti-rust barrier on the surface(and covering the penetrol).

I’ve put one coat of JPW on the jointer’s beds to protect them, and the fence is now soaking in evaporust. I have the zyalox brushes and will clean the fence up when it’s done soaking. I have to pull the beds apart and the cutter out to clean things up and wax like Russ suggested.

I’ve looked for Penetrol but can’t seem to find it here in San Diego. Is there an alternative?

Majones1 wrote: ↑Sat Aug 28, 2021 8:54 pm I’ve put one coat of JPW on the jointer’s beds to protect them, and the fence is now soaking in evaporust. I have the zyalox brushes and will clean the fence up when it’s done soaking. I have to pull the beds apart and the cutter out to clean things up and wax like Russ suggested.

I’ve looked for Penetrol but can’t seem to find it here in San Diego. Is there an alternative?

Home Depot in San Diego has it or Amazon.

Edit:
Sorry it is unavailable at the store and unavailable for DELIVERY, but it is still listed on the San Diego store web site. Probably another Cali law preventing sale of things that the rest of us can get in the rest of the country.

Order it from Amazon unless they won't ship it to Cali.

I buy mine at Ace Hardware, most local stores seem to have it. I'd check with them unless CA different then IL.

Ed

CA is different from everywhere else.