The industrial look of unpainted steel is becoming massively popular. Given that steel will rust over time, sealing off the metal is really important.
Even if you want a rusty look, unsealed steel will just turn brown-orange, smear on everything, and make an absolute mess. You get instant “garage-hands” from touching it.
I’ve tried a very large quantity of products that have been complete disasters. The most common problem is chipping and peeling, which is the absolute worst. You can also run into issues with discoloration.
In this article, I’m going to give you some great tips on how to get the exact look you want with your steel, AND how to keep it clean and permanent.
The Cheap, Easy, and Awesome Solution
If you don’t want to read and just want a quick, easy product solution, here it is:
Buy a can of Penetrol on Amazon.
Clean the metal thoroughly, brush on, let dry, enjoy.
The only thing I’d strongly recommend is that you do this in a well-ventilated area, and use a paint mask and gloves. This stuff is pretty noxious when it’s wet. Some mineral spirits will also help with cleanup.
To be clear, I have no affiliations with Flood, the company that makes Penetrol. I just really like the product. At the end of this article, I’ll include some other options for finishing metal furniture.
Why This Stuff Works So Well
Previously, I’ve had absolutely miserable results with different kinds of lacquers, acrylic spray paints, polyurethanes, etc. There are few things worse than having a projects that you’ve sunk hours and hours into just peel itself into a horrible mess.
Of course, properly prepping the metal is absolutely critical. But you also need something that lasts for years.
So why is Penetrol such a good product for this?
Funny thing, this is actually a paint additive, but then people realized how great it is for finishing metal.
Anyway, this stuff really bites in. It’s a type of penetrating oil, so it seeps into every little pore of the metal and does a great job of bonding.
It goes on fairly easily, too. It’s a bit thinner than most of the urethanes that I’ve tried. You can work it into a nice, thin coat even with a paint brush, although you will see brush strokes (tips on that later). The finish is along the lines of a gloss/semigloss, although there are ways to tweak that.
It usually cures in about a day, although it’ll take longer if it’s colder. Don’t use it if it’s below 50 degrees.
Tips for Finishing Metal with Penetrol
For the most part, this is pretty easy stuff to work with. There are a few tips worth noting, though. Especially if you have a particular look you’re trying to achieve.
1. Paint your furniture in a dust-free area.
Penetrol is pretty slow-drying. After about 8 hours, it’ll still be noticeably tacky. That means that any dust in the air will have all the time it needs to stick to the finish. This is especially important if you plan to keep the finish glossy.
2. Brush lines will show.
If you apply Penetrol with a brush, you’ll have to really work it to reduce the visible brush strokes. Even with a bunch of effort, they’ll still probably be visible.
This is kind of funny, because Penetrol is intended for use as a paint additive to reduce brush strokes. Kind of counter intuitive.
If you absolutely don’t want brush strokes, try applying it by spraying.
If you don’t have that option but still want to reduce the brush strokes, try applying it with a super fine steel wool, like this one.
3. Don’t apply this over heavy, loose rust.
If you WANT the metal to keep its rusty appearance, this product still works great. You just have to hit the metal with a wire brush first to knock off anything that’s loose. I’d highly recommend using a wire wheel on an angle grinder to power through it effectively.
4. If you’re brushing it on, use a small container.
This is especially important if you’re working on something that has any kind of rust.
Penetrol will grab on to anything loose on the surface. It’ll stick to your brush, and then mix with the fresh Penetrol as you dip your brush back into it. This will result in some imperfections in your finish.
I pour the fresh Penetrol into a disposable beer cup. I fill it up about 1″ and work with that, then dispose the cup and pour a fresh one.
It might sound a bit wasteful, but it’s really not. A little goes a long way, so for something like a coffee table, you might only use 2-3 cups.
5. Penetrol can slightly change the color of the metal.
Especially with thicker coats, you might end up with a very subtle brownish-yellow color. It’s usually barely noticeable, unless you’re really scrutinizing a before and after of the metal.
It’s always a good idea to try any coating on an off cut before you commit to coating something completely.
6. Use ultra fine steel wool to get a matte finish.
If glossy metal doesn’t do it for you, you can lightly buff out the shine with some 0000 steel wool. I’d recommend waiting until the finish is COMPLETELY dry (I’d wait 2 days instead of 1 just to be sure).
Then gently go over all the surfaces with the steel wood and water. I like to do a hatched pattern with the strokes so it’s more uniform. Clean it off with a soft, clean cloth.
This can also be a backup plan in case you did end up getting dust imperfections in the finish. The steel wool will hide and buff out the dust particles.
7. It works on more than steel.
This will also work on metals like copper, brass and bronze, even if they have a patina. I haven’t tried it on aluminum yet, so I can’t make any recommendations there. I’ll put that on my to-do list. I usually leave aluminum bare, though.
It’ll bond well to other things, too. Even glass. In other words, watch out for what you might drip it on.
Alternatives for Finishing Metal Furniture
There are definitely a lot of ways that you can finish bare steel. Penetrol is just my personal hands-down favorite.
You can try other spray on or brush on clear coats, like acrylic or urethane paints. In the past, I’ve had issues with these chipping, but they can work with low-traffic pieces that aren’t exposed to wear and tear.
There are also a lot of other spray-on and paint-on options for clear coats, but I have yet to find anything that outperforms Penetrol, and they all seem to be noticeably more expensive for comparable results.
If you’re looking for something different, like a black finish, you might want to look into a burned oil or beeswax finish. These can look really cool, very similar to a seasoned cast-iron pan.