Introduction: Archaeology: Refinishing the Trowel

This is a continuation of another Instructable, Archaeology: Repairing and Modifying a Trowel

I started writing this as a second part to the step-by-step above, but it quickly seemed like this was two separate projects. This will guide you through a basic application of Traditional Black Magic Patina as well as staining and sealing the handle. The result gives the tool a sort of antiqued look, by oxidizing and staining the metal as well as giving the wood handle a darker hue. Whether you are digging an archaeological site or doing some weekend garden work, you will be awesome! That being said, this Instructable has very little to do with Archaeology itself, this is purely cosmetic.

As usual, this was all done at TechShop San Jose! The Sandblaster as well as the other facilities make this project much easier to accomplish. However, if you aren't near a location refinishing like this can easily be done at home (it just takes a bit more elbow grease to prepare the metal for the patina).

To use the Sandblaster, a Safety and Basic Use (SBU) course is needed.
Other Tools or Materials Needed:
  • Black Magic Patina
  • Wood Stain of your choice (I used Cabernet and Dark Walnut)
  • High Grit Sand Paper (low number <100)
  • Low Grit Sand Paper (high number >300)
  • Masking Tape
  • Scotch-brite pad (for scraping off too much patina or to clean surface without sandblaster)
  • Sponge or Paper Towel (To apply Stain)
  • Gloves

Step 1: Preparing the Metal

The easiest way to clean the metal surface before finishing it is taking the trowel to the sandblasting cabinet. The way I like to think about it, is that it is a pressurized rapid sanding tool. Using compressed air and aggregate material to blast of the top surface of metal or whatever object you are sanding. Highly efficient at removing rust or grime, this tool is crucial for convenient finishing such as a patina. powder coating or painting.

Since the trowel is so small. it does not take very long to clean off the entire surface. Be sure to be careful of blasting the wooden handle! While there is a later step to sand off the original finish, the sandblaster will remove a bit too much material from the tool. At TechShop, it is standard procedure to wear some sort of gloves (I just used nitrile myself) when using the sandblaster. Since it is one of the tools in the shop that get used often, the dirt and grime from projects builds up in the cabinet's gloves which is unsanitary. The tool is pedal operated and it's basic use is covered in the SBU mentioned earlier.

Once the sandblasting is done, the metal will be cleaned off and will be a dull grey color, as opposed to the shiny quality it has after grinding. Keep in mind, if you are intending on putting an edge on the trowel as mentioned in the last instructable, be sure to sandblast first or be prepared to put another edge on it. (I learned this the hard way).

You are now ready to apply the patina!

Step 2: Patina and Clearcoat

I highly recommend using gloves for this entire step, as stated on the bottle, the patina is a toxic finish which can irritate the skin. Not only that, but any oils will hinder the effectiveness of this solution. Be sure to do this in a well ventilated area, the only reason why I am using this indoors is that I am only using a small amount at a time. If you are using this for another project keep in mind that anything more than this will require proper ventilation. 

The first step to staining the metal is to mask off the handle of the trowel. The handle was sealed when I bought it, so it was unlikely that there would be any damage to it; especially since I am refinishing that anyway. However, when going to clear coat I would prefer to have the handle masked off to make it easier for later.

I applied the patina itself by getting the solution on a folder paper towel (as if you were applying rubbing alcohol or hydrogen peroxide to a wound), and rubbing it on to the metal. Patina stains the metal and has oxidizing agents to give it an antiqued look, it can be diluted to be weakened or applied straight. It can be applied hot or cold, and will produce different results with what you choose. for this, I applied it straight and cold and I am curious to see what it looks like with other finishes. When I do get a chance to do that, expect different variations at the end of this. 

In the third image you can see what it looks like as it is applied; a glossy turquoise and copper color. If the stain gets too dark, take a scotch pad to scratch off the patina and try again. I did this several times until it came out to the color and intensity that I wanted. Also, take your time! There really is no rush with applying the patina, the longer you wait before clear coating the more rust will occur. Depending on how old you want it to look, the longer you should wait. After you are satisfied, wipe off any excess and allow to dry; you are now ready to seal it!

Now, the clear coat I had on hand wasn't optimal for what I was doing here. It darkened the metal to a dark emerald green sheen, which is cool, but not quite what I was going for. This could have been the reason for the darkening, or it could be the intensity with which I applied the patina. I will update this as I refinish more of my school's tools and get more information through experimentation. Either way, wait 30 minutes to an hour between each coat of finish (or whatever the can says). I put three coats on, but the more coats you have the more resilient the tool will be in the field. Another thing I found out is that the more coats that are applied, the more the edge is dulled. It's not too badly dulled, but you may want to mask the edge off when clearcoating; your choice really. 

Now for the handle...

Step 3: Refinishing the Handle

Before starting this step, make sure your clear coat is completely dry before touching it. It is easy to leave finger marks, even with gloves, on the surface. For this reason, I masked off the blade for this step just so I could easily handle the tool without worrying. 

I first sanded off the existing finish on the wood with some high grit sand paper. Quickly going over the entirety of the handle, getting off any polyurethane, dirt or anything else on the surface. I then went over a second time with the low grit sand paper, making the surface as smooth as possible. Be sure to go with the grain of the wood in order to produce the nicest quality of stain.

As with the clear coat, I stained with whatever I had on hand. The result was that I mixed stains to produce the color I was looking for, somewhere in between the red of the Cabernet and the dark brown of the Dark Walnut. For myself, this has opened up a new possibilities with experimentation with stains and mixing them in different combinations and intensities! For yourself, do whatever you want! There are many different stains to use, such as buying the color you want rather than mixing.

To apply this, I once again used folded paper towels with which I dipped in to the stain and rubbed on to the wood. I mixed the two by alternating between the Cabernet and the Dark Walnut. I did not wait for the stain to sit before rubbing off excess, I either wiped off the handle immediately or just applied the other stain on top of it. I mixed the handle to taste really, until the dark cherry red that I was looking for occurred. 

After this was done, I waited for the stain to dry fully, then took it back to the spray booth at TSSJ to apply polyurethane. To avoid getting bristles from a cheap brush embedded in the seal, I used a spray on water based sealant. Nothing too fancy, but I just did 3 or 4 coats to ensure that it would be durable in the field. There is a rotating rack available in which I put the blade in to to suspend the handle, making it easier to coat.

Allow to dry over night, and then you are finished!

Step 4: Finished!

And there you have it! A way to not only find your trowel amongst a sea of the mundane, but also to make it look cool and antiqued. In your own nerdy way you can feel like an archaeologist from the 19th century, but not really, at all. Next project that will be published will definitely have more practical use in the field, 2 different variations on personal soil screens and a larger screen for dry or wet screening!

Be sure to check back in for a better photo of the finished product as well as alternative application methods for the Black Magic Patina! Comments or suggestions are definitely welcome, this is a documentation of the procedure I followed.

If you have a spare moment, be sure to check out your local TechShop, or see if one is on its way to your area!

The Patina I used can be found on Sculpt Nouveau's Website.