Because, SCIENCE.

Scrounging around on eBay a while back, something caught my eye. An old rip saw – not rare, not beautiful, not exotic… but in obviously good condition once you saw through the neglect. It is (I believe) a Disston D-8 No. 7, which likely places it somewhere between 1876-1928.

Note: See comments below for correction.

a

It had terrible rust, but the seller had photographed it well enough to show that the applewood handle is intact and uncracked, the teeth are in fine shape – honestly, I don’t think it was sharpened since it was purchased – and the nib is intact. That doesn’t matter all that much except aesthetically, since apparently nobody knows what the nib was actually for.

B

I’ve used one of these in the past. Much as I love my bowsaw (not surprising), there are times I need to make long rip cuts where the frame of the bowsaw gets in the way no matter how I juggle. A rip panel saw is a tool I need a few times a year. But there are problems:

  • Good ones are expensive. They’re fantastically beautiful, but I just don’t use it enough to justify the expense.
  • Cheap ones are awful. They come razor sharp from the factory, but they don’t track well, and they’re a grade of horrible plastic handled monstrosities that I just can’t bear to use.
  • Vintage saws often look like this. Often bent blades, broken handles, rust, broken teeth, missing nib. Note that this one is sold as a “decor piece” for about $64 USD.

The one I found on eBay met all my criteria… for $7.95 + free shipping.

The Journey

My goal wasn’t to make it pretty. It’s not a decoration. I don’t care if the blade is shiny, as long as it’s smooth, straight, sharp, and free of rust. Once the handle was removed, I thought about making a new one out of a beautiful piece of burl mesquite I have on hand.

Why? This one is banged up, but is completely intact, and has no signs of rot. I decided I liked the way it felt… so I cleaned the gunk off with some mineral spirits, gave it a couple of coats of danish oil, and ran it across the Beall Wood Buffer. Voilà.

C

The Science Part

Evapo-rust works fine. I’ve used it in the past… but when I tried it on an old tool with an engraving, the etching came out almost indistinguishable from the rest of the tool – not damaged, just exactly the same color. I couldn’t tell if the blade had etching or not (it didn’t). I wanted to try electrolysis on this one. I’d read about the method for a long time, and I had everything on hand.

I’m not going to write in detail about this technique. It’s covered extensively online.

Short version: Washing soda (not baking soda, or salt, or anything else) at about 1 tablespoon per gallon of water. A chunk of steel (the anode) that gets sacrificed in the process. Leads for a battery charger. Negative lead connects to the tool. Positive lead connects to the sacrificial steel anode.

Anode

The Bath

Mandatory points of caution:

  • Don’t let the electrode and the tool touch. That’s a BAD electrical thing.
  • DO NOT USE A STAINLESS STEEL ANODE. IT WILL RELEASE HEXAVALENT CHROMIUM, WHICH IS TOXIC
  • Kinda be careful about electrical leads in water. Like, don’t get your hand across them. Unplug the charger to make adjustments.
  • Don’t smoke. Don’t do it in a confined area. The little bubbles are hydrogen – which can be kinda-sorta-flammable.

How it works: The  sodium carbonate (washing soda) makes the water more conductive. When it’s dissolved in water, it releases becomes sodium ions (Na+) and carbonate ions (CO3 2-) .  These positive and negative charged ions carry the current in solution – the carbonate moves to the anode (positive wire) from the battery charger and sodium moves to the negative wire. The result is that the corrosion and rust moves off the tool to the anode.

Scrubbing Bubbles

Almost immediately after connecting the charger, you’ll see little bubbles rising off the tool. That’s the hydrogen I mentioned earlier. It’s tiny amounts, but I’m still not going to light a cigar around it. After about two hours, the tub looked like this:

f

That’s rust and gunk removed from the blade. Gross, but not toxic – you can actually dump the water out on the grass (it’ll love the iron). I had to stop the process and scrape the worst of the debris off the anode, so the electrical connection stayed solid.

This is the 24-hour point:

g

The Result

The rust on the blade is replaced by a black patina. It comes off pretty easily with steel wool or scrubbing pads. It’s harmless, and doesn’t affect the blade. You can scrape it bright or leave some of the patina. For this saw, I wasn’t very picky about making the metal bright again.

h

The brass nuts cleaned up in a few seconds with a little Brasso. One point – save yourself some fumbling putting them back in by marking which one came out of which hole – they’re not all exactly the same. A wipe down with Camellia oil finished the blade. I may return to the blade later and remove more of the patina… we’ll see.

Sharpness

One stroke with a file was all it took to bring the teeth back to good condition. That’s a good thing… because I HATE sharpening saws, and I’m not very good at it. Rip saws are at least a lot easier than crosscut, but it’s finicky work and I pretty much wrecked a crosscut saw and had to have it professionally ground and resharpened.

j

At first, this one didn’t really want to track well in the cut. I took an Arkansas stone to both sides of the teeth to take the set down a little, and it cuts fast and accurately.

Since I had a plastic tub on hand, total project cost:

  • Saw: $7.95
  • Danish Oil: On hand
  • Steel for anode: On hand (rebar works just fine for this)
  • Camellia Oil: On hand
  • Battery charger: On hand
  • Washing soda: $4.25

Total: $12.20. And a beautiful day. And a new (not-new) panel saw in the till. Can’t beat that.

Ross Henton

June 2019