How to Protect and Seal Unpainted Mild Steel.





Introduction: How to Protect and Seal Unpainted Mild Steel.

About: amateur mad scientist, who loves to tinker and create

How to protect mild or non stainless steel if you want to keep the raw metal look on your furniture.

Step 1: Making Metal Furniture.

I started this project some time ago when I wanted to build an entertainment center out of wood and metal for that industrial look. building it was a lot of fun and a great learning experience. However sealing the metal became a bit of a challenge after some trial and error and some research I discovered Penetrol.

Step 2: Supplies

This is all the stuff your going to need.
Penetrol is an additive for oil paint it's supposed to remove brush marks and increase the working time of the paint. I found that it works great to seal metal it is transparent and very durable. I tried clear acrylic spray paint but it was weak and chipped easily. Penetrol is pretty cheap and a little goes a long way it is usually in the paint section of lowes or home depot and is around 10 bucks a can.

Brush and container. it's pretty self explanatory your going to need something to apply the stuff I found chip brushes and plastic containers at Harbor Freight for really cheap you can buy the expensive stuff if you want but I'm cheap.

Respirator and paint thinner. optional but recommended. This stuff is pretty stinky so you might want a chemical respirator I got this one st harbor freight for around 15 bucks it works great and I use it all the time for other projects. Paint thinner is just in case you want to reuse your paintbrush and is completely optional I store a small amount in an empty paint can with a lid for rinsing brushes.

Step 3: Applying

This stuff is really easy to work with just apply it like paint make sure you cover all cracks and sides.

you might want to practice on a small piece to see how it looks like in the first picture you can see a slight difference in shine. but the unpainted part is already getting rusty but the painted end looks fine.

This stuff takes around 24 hours to be dry to the touch but will feel sticky for a little while because it needs a week to fully cure. once fully cured the stickiness will disappear.

I hoped this helped good luck!



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    13 Discussions

    Good Instructible, I think it will be useful to many people!

    I build furniture and use mild steel often for it's low price, availability, and workability. I went though a similar process of trial and error, and here's my best process:

    There are usually two "ways" your steel can be-- new, in which case it will have an oily film and a hard scale on the surface; or it will be 'not new' meaning it will be rusted, aged, 'patina'd' (if you're trying to sell it haha), etc.
    If the oil film is palpable, I begin by rubbing it off with sawdust. In either case, my next step is to remove the rust and to scale to achieve my desired look using the maroon-colored 3M abrasive pad. After that I blow off the dust with pressurized air, and wipe down with mineral spirits and a clean rag. Removing the oil is key to any good finish.
    After the prep work is done, I'll apply a clear coat in one of two ways. I have had good results with spray can poly; with this the most important things are avoiding over-application and applying it in a favorable environment (not too cold, not too humid, and not windy so as to avoid airborn particles to contaminate the finish as it cures). The other clear coat I use for steel is gloss lacquer, thinning with lacquer thinner until I avoid leaving brush marks. I usually start at a 1:5 mixture. It's worth mentioning that I find it to be a waste to keep any kind other than gloss lacquer on-hand; you can always lightly buff a cured coat of gloss lacquer with '0000' steel wool to tone down the gloss if you think it's too shiny. Hope that helps some people; I've found it to be an efficient, quick, and versatile combination of materials and technique and it's worked very well for me and the several pieces I've used it on. I'll try the Penetrol if I get a chance. Shellac might be a good option or outdoor use, otherwise try some spar urethane, which is intended for outdoor longevity.

    I generally use boiled linseed oil and Johnson's Paste floor wax (JPW). I wipe down and use mineral spirits for tack cloth and then once dry, apply the linseed uncut. After it dries a bit I work JPW into the mix and buff it by hand once hard.

    BTW, this works great for "sealing" the patina on old cars, too. My truck has barely a sheen, but water beads up like crazy! Generally re-apply the wax once a year on the cars, couple of years on other stuff - great for outdoors.

    2015-09-27 16.54.58.jpg

    Fish oil is very good but may smell for a while

    in Germany also called Owatrol. you can Google for hours and douzens oft sites where the ingrediants are discussed. seems so that its only linseedoil and terpentine. easily made by yourself. i usw it for years to conserve my car

    I'm going to check out Penetrol when I go to the hardware store. I have been using 1 part boiled linseed oil mixed with 2 parts mineral spirits. I apply with rag and/or brush and wipe it down well. I also use it on bare steel that is outdoors. It works well.

    If you try it, be sure to allow the rag to air dry. Don't wad it up and put it in the trash because it could be a fire hazard.

    2 replies

    does the boiled linseed work well for outdoors? I haven't tried the Penetrol on anything that will be outside yet if you try it let me know how it goes

    I use boiled linseed oil on steel and cast iron items that are outside. It seems to help keep them from rusting and gives them a nice sheen. I use it on wood quite a bit but I'm not sure how well it protects the wood that is exposed to weather.

    At our hardware store they sell 2 types. Raw and boiled. I use boiled because it hardens faster than raw.

    It is made from flax seed. There is a good article in Wikipedia which pretty much explains anything you might want to know about it's uses.

    I am careful to take linseed oil soaked rags outside and lay them out flat to dry because I have heard that it can be combustible if wadded up sitting in the trash.

    Called owatrol in the UK... Same stuff. Good article for people new to working with mild steel who might buy the clear coat spray cans from halfords and end up disappointed.


    2 years ago

    good stfuff - we also get this in Australia and have been using this method for a while to preserve the look of either new or rusted mild steel. My only caveat is that once cured it can look a little shiny so be careful if you want more of a Matt finish. To me it also has a finish like a varnish, ie it has is a perceptible coating you can feel. However that may just be because I paint the stuff on fairly liberally!! For a lighter, but probably less heavy duty finish on mild steel, I can also recommend a light coating of Danish oil for anything that isnt going to be exposed to the elements.

    I think over here it's also marketed as a good primer for metal as well although I haven't used it for that yet.

    The tiny bit of moisture left by your bare hands on the raw steel before finishing can often lead to rust "spiders" appearing under the finish. Having done this type of work a LOT in the past I have found that it is best to plastic wear gloves when handling the bare metal. I have found that a final rubdown with a scotchbrite pad and then cleaning solvent like alcohol, all while wearing fresh disposable gloves, goes a long way to prevent the blemishes that develop over time on steel covered with just a clear coat.

    1 reply

    hmm thanks I never thought about that thanks for the tip!