Removing rust – chemical methods

When it comes to chemical rust removers – there are two main methods: spray-on/gel or soak. To get an idea of the acidity level of each of these solutions, here is a list of their pH values – the closer to 0, the more acidic a solution is (water has a pH of near 7).

Evapo-rust 6.1
Molasses 4.5-6.0
Acetic acid (vinegar) 2.4
Citric acid 2.2
Lemon juice 2.0
Oxalic acid 1.3
Phosphoric acid (naval jelly) 1.0
Muriatic acid (HCl) 0.1

The amount of time it takes to dissolve or neutralize rust depends on the amount of rust, and the concentration of the solution used. Objects should be periodically removed, and the gunk scrapped off. Note that very few tools are uniformly rusted, so rust will be removed at a differential rate. Treated steel can rust very quickly after exposure to air – rinse, dry, and treat immediately.

1. Vinegar

The simplest form of chemical rust remover  is household  vinegar, which is usually about 5% acetic acid. Acetic acid is also known as ethanoic acid, with the formula CH3CO2H. Vinegar will leave a grey finish that is a type of rust crystal that adds a small degree of rust resistance. Iron (III) oxide reacted with Acetic acid will produce Ferric acetate and water.

Fe2O3 + 6CH3COOH → 2(CH3COO)3Fe + 3H2O

Sometimes baking soda is used after the vinegar to neutralize the solution. Note that vinegar is mildly corrosive to metals, including iron, magnesium and zinc (acetic acid + iron = iron acetate + hydrogen). It also works extremely well for cleaning and sharpening files.

2. Citric acid

Citric acid is a very weak acid, but marginally stronger than vinegar. A 10% solution is adequate, so 100g of citric acid with 900ml of warm water (which works faster than cold water). Once the object has been placed in the citric acid, bubbles will start to form which means the citric acid is working. Citric acid + rust yields iron oxide, carbon monoxide, water and hydrogen.

C6H8O7 + Fe2O3 → 2 FeO + 6 CO + 2 H2O + 2 H2

NOTE that citric acid etches iron and steel – if you leave things too long microscopic etched pits can form. Lemon juice is slightly more acidic than vinegar, and has a similar effect on rust.

3. Molasses

Molasses made from cane sugar is acidic (beet molasses has a pH of 8.0). There are a number of ratios of molasses to water in the literature –  1:4, 1:6 or 1:9. Molasses such as Crosby’s Fancy molasses has a pH of 4.5-6.0 (with a 1:1 dilution). The water and molasses mixture, when exposed to air ferments, producing acetic acid, amongst other substances. The downside to molasses is that it is incredibly slow – it may take a week or so. Molasses won’t remove as much steel if you leave it in the bath too long.  It seems to be the most gentle.

4. Evapo-Rust

Evapo-Rust is a commercial product that works by chelation, bonding to iron. An iron chelator is a chemical that forms a soluble, complex molecule with certain metal ions, inactivating the ions so that they cannot normally react with other elements or ions to produce precipitates. This process does sometimes leave a black film on the iron, the longer the item is in the solution, the darker the film becomes (this black film is supposedly carbon).

Evaporust is everything one could want in a rust remover – non-toxic, no fumes, biodegradable. Amazing stuff. Could be expensive for large items.

5. Oxalic acid

Oxalic acid is an organic compound with the formula H2C2O4.  In common use it is found in a product called  Barkeeper’s Friend. Barkeeper’s Friend can also be used in a paste form by shaking some  onto a damp rag, rubbing it all over the surface and leaving it for 10-15 minutes. This is supposedly extremely good at removing rust from chrome plated surface.

6. Restore Rust Remover

A new product, Restore Rust Remover Gel, is from the UK. A gel is great for applications where a wooden handle can’t be easily removed in order to submerse the entire tool. The product contains both etidronic acid, and trisodium nitrilotriacetate. Both are chelating agents, pH neutral.

7. Naval Jelly

This is a strangely named product is actually just phosphoric acid (H3PO4). Naval jelly may have been one of the first commercially available rust removers – advertised in Popular Mechanics in the 1960s, and was available in 55-gallon drums. The phosphoric acid will convert iron oxide Fe2O3 to iron phosphate FePO4.

Fe₂O₃ + 2H₃PO₄ yields   2FePO₄ + 3H₂O

Other chemical methods

It is possible to use chemicals like hydrofluoric acid (HF), hydrochloric (Muriatic) acid – but used incorrectly (like in the wrong concentrations) both are likely to etch the iron. These chemicals have relatively harsh fumes associated with them, even in low concentrations. I would avoid the more dangerous acids in rust removal – they aren’t necessary. What about Coke? Is it at all possible to dissolve rust in Coca Cola? Possibly – it contains high levels of phosphoric acid, Coke has a pH of about 2.7.

If the rust is really ingrained, then you can build a DIY electrolysis system. Electrolysis is a method of removing the iron oxide by passing an electrical charge from a battery through the rusty metal to stimulate an exchange of ions while the tool is submerged in an electrolyte solution. For items such as saw blades it may be easier to scour the surface with synthetic steel wool/fine 400-800 grit wet-and-dry sandpaper and mineral spirits – not really chemical so to speak, but involves the use of a chemical as a lubricant.

Stay tuned for the experiments!

Making a Viking chest

Interested in making a Viking style chest? Not going to Woodworking in America (in Kansas City – well worth the trip)? Lee Valley’s downtown Toronto store is running a 2-day seminar on September 25th & 26th titled “Make Your Own Viking-Style Chest“, run by Steve Der-Garabedian. I made a hand-plane in one of his workshops a couple of years ago. I wish LV ran more of these seminars… maybe some seminars that run week-long? Building a bench maybe?

Anyways, I have signed up to make this Mästermyr – style tool chest, should be a load of fun! Now just have to do some reading up on the chest.


Vent backdrafting

Continuing on from my last post, I had a little gem arrive in the mail today. Both my bathroom vents have internal butterfly dampers which stop the cold air in winter backdrafting into the house. The dryer has never had a backdraft preventer except for the the insulated foam vent cover (EcoVent), which honestly never worked well. Metal butterfly backdraft mechanisms are just a recipe for lint build-up. Now that the vent cover has been replaced, I was looking for a backdraft preventer.

Enter the Cape Backdraft Damper from Tamarack Technologies. It apparently opens and closes with minimal airflow in either direction. The problem with other dampers is that in some way, most of them restrict airflow. That’s not the case here. The airflow from the dryer is the same as it was before the damper was installed.


The 4″ model fits snugly into the dryer vent, and is super easy to install – it took 1 minute tops. Air flows freely through the backdraft preventer with no fear of lint build-up. The real test? How much cold air will enter the dryer in the winter when it’s not running? I’ll get back to you on that. If it works well, I might just replace the butterfly backdraft preventers.

Needing to vent

Whilst renovating my house, I have always tried to use products which are efficient. Over the years I have tried various vent covers for both the dryer, and bathrooms. I don’t like the one with plastic flappers, or louvers – one basic word describes them – garbageThe main purposes of a vent cover is to (i) allow for unrestricted air flow out, and (ii) stop air coming in, i.e. backdrafting. If used for a dryer, it should also not catch lint that somehow escapes the lint trap in the dryer (like seriously can someone not design a lint trap that actually catches all the lint?). Oh, and it should be strong, and maybe not just white, other colours would be nice.

So the first vent cover I installed over 10 years ago was the insulated foam cap, the Broan EV100 EcoVent, shown in Fig.1. This vent uses a “floating ball check valve” to block the vent when there is no air flow, and when air does flow, the foam ball is lifted out of the way. This vent seems like a good idea, however it needs considerable airflow to keep the foam ball aloft, and if used on a dryer vent, lint tends to build-up on the enclosure. It is supposedly airtight, but the foam ball never quite moves as seamlessly as it should in its enclosure, meaning that there are gaps in the seal. Fluctuations in the air being expelled cause the ball to quiver in its enclosure, causing an annoying rhythmic sound – dispelling any notion that the device is noiseless. I found over the intervening 10 years that the airflow from bathroom fans (which is way lower than that of a dryer) is reduced because of the foam ball set-up. Lastly, the information on their website suggest the vent cover is attractive, yes it has nice curves, but it tends to create a series of “bumps” on the side of the house. It was a good choice, for all the solutions available at the time. Home Depot use to carry them, but now they seem to have disappeared from the market.


Fig. 1: The EcoVent from the outside and the inside

About a year ago, I swapped the dryer vent out with an all metal vent, like the one shown in Fig.2. I have a similar one on my range-hood and it seems to work well, so I assumed it would work well on the dryer. The design touts a 100% gasket seal, airtight construction, and a weighted damper to prevent back-draft. Due to the warm air expelled by the dryer, the gasket seal continuously fell off. Worse though, the opening has a wire mesh cover, which is a honey-trap for lint. Lint also becomes caked on the inner walls of the vent.


Fig 2: The metal vent, with lint build-up.

So, looking for a new vent cover, I came across this simple design, the DryerWallVent. The Dryer Wall Vent (DWV) has an extremely low profile, is made of galvanized steel, and wait for it – it comes in more than one colour: tan, brown and white. So aesthetically, it is a great looking vent. It also has unrestricted airflow. Now it doesn’t prevent backdraft completely, but the vent should have some form of backdraft preventer inside the duct (see next post). The integral magnets prevent pests from gaining access and negative pressure flapping.


Fig 3: The Dryer Wall Vent package

The benefits? It’s incredibly simple, and it works. There is nothing restricting air flow, so the number of cubic feet per minute for the particular device in question is not restricted. When there is no airflow, the cover closes the vent off. It doesn’t flap in the wind.

Installation is incredibly easy. As I was retrofitting vents in a house that’s nearly 90 years old, I also opted for the 1″ offset base (AZEK solid cellular PVC mounting block). While technically it is suppose to help with offsetting a vent where there is siding, I used the base to make installing the vent over holes which weren’t perfect to begin with. The example shown below is the retrofit of my basement bathroom fan vent (with an integral butterfly damper). The pipe is slightly oval in shape due to a misshapen hole.


Fig 4: Retrofit hole in wall, and addition of PVC mounting block.

Once the PVC block is mounted, it takes about a minute to attach the vent itself, using four holes on the inside of the vent. I attached it using stainless steel screws. Notice there is a gap between the vent and the ducting in the photo below. I merely used aluminum ducting tape to create a seal between the two. Below you can see the DWV in action. To finish it off I caulked between the cover and the PVC block, and the block and the wall.


Fig. 5: FiDryer Wall Vent attached to PVC block, and in action.

The company also carries an excellent range of dryer-boxes and other accessories for venting. To date I have installed two vents, one on the dryer, the second on one of the bathrooms. Still waiting to find the time to do the second floor bathroom (largely because it involves siding).

Iceland – land without trees?

We visited Iceland in the summer of 2013 (see my other blog for particulars). One of the things that really stood out for me was the vastness of the volcanic landscape. Put another way, the distinct lack of trees. Iceland, was once (well 2.5 million years ago), covered in coniferous forests. Over the years, and glaciations, the number of tree species gradually reduced to the point where, at the time of human settlement in circa 900AD, there was really only birch forests and willow scrub left. At this point, 25-40% of the land mass was covered forested, however it didn’t take long for the forest to disappear due in part to sheep grazing, clearing of the woods for pasture, firewood, charcoal and construction poles. By 1950 the birch woods covered less than 1% of land area. But the lack of trees isn’t because of the cooler climate. Canada is colder, and we have heaps of trees.

Afforestation is progressing, but at 1.5% of land area, forests still aren’t that widespread. Tree species have diversified. In addition to mountain birch, there is also Russian larch, Sitka spruce, lodgepole pine, and western balsam poplar. But, maybe not enough to sustain a large lumber industry.



  • Largest forest in Iceland: Hallormsstaðaskógur, 1854 hectares, 70% native birches, 30% imported species.
  • Forests cover 49,000 hectares.
  • About 200 tons are harvested annually.
  • There are no mosquitoes in Iceland (or snakes for that matter).
  • Iceland’s first apple tree was planted in 1909.

How expensive is lumber? Here’s a quick comparison with a piece of standard building lumber in North America: the ubiquitous 2″×4″ (normally spruce in Canada, but sometimes fir). Looking at the catalog of the Icelandic version of Home Depot, Bauhaus, the closest equivalent is the 45mm×95mm, and the price per metre is 390 Krona. This is equivalent to about C$3.74. So an eight foot length is about 2.44m. A 2″×4″×8′ at Home Depot in Toronto is C$2.60. The equivalent piece of lumber in Iceland would cost C$9.30. Yikes… and that’s just for a crappy piece of building lumber. I don’t imagine there are too many places selling exotic lumber either.

Any Icelandic woodworkers out there?


The Boston trio

Some of the most unusual block planes are “THE BOSTON” brand, made from aluminum in the United Kingdom. Are they named after Boston, Lincolnshire, or related to “The Boston Vice Company”, part of Tilgear? As there is next-to-no information regarding these planes, I am going to imagine that there aren’t any more models out there, bar the three already in my collection. From the use of aluminum, I would surmise that they might have been manufactured circa the 1950s. The only non-aluminum parts are the screws, cross-bars, and of course the blades.


The No.1, No.2A, and No.2

What influenced the design of these planes? The body of the No.2 and No.2A are identical, it is only the lever cap that differs. In some respects, the planes do have, what some would say are ergonomic features. The No.2A in the centre even has vestiges of a streamlined form. The No.2 (as shown below) incorporates a rabbit-ear like lever cap, which allows the purlicue (like who knew the part between your thumb and forefinger had a name!) of the hand to rest, and apply forward force.


Holding the No.2

They are the most colourful of planes: red, blue and black (the 2A shown in the middle is more commonly seen sporting black). The paint may have been used, both as a sales gimmick, but also to cover the rough surface of the plane, as little effort was put into milling the surface and making it a “quality” product. The weird thing about these planes it that none of them show any markings beyond “THE BOSTON”, and “No.2″/”No.2A”.


An example of the rough finishing on the aluminum