In the week between holidays I took some well-deserved time off to enjoy the holidays and just be. For me that included a list of random errands I normally can’t get to M-F, after which I headed back to my shop to get a little work done, starting off with some milling about before settling down to the task I felt most important at that time. This consisted of finishing up friends’ and customers’ saws for restoration, including some finish glazing, a plate replacement, and some sharpening as always. I think sharpening and plate sanding are something I always have at the ready.
Plate replacement requires the use of the retoother most times, as well as setting up space for sanding, so I find it best to batch my work. I normally have a few backsaws of my own ready and depending on what’s in the shop or my mood I’ll process a few. In this case I had a really nice double eagle 14” that needed a new plate as well as an 18″ brass backsaw of my own that was waiting for a new plate after completing a handle repair.
So with that in mind I pulled out some of the plate I cut, or should I say I helped cut, a few weeks ago and got out some vinegar and a plastic tray.
I left off with the finished plate cut to size. The next process is removing the blueing that is applied to prevent the rust. This can be done a few ways but so far I’ve been following a process I got from Isaac of Blackburn Woodworking. First I degrease the metal with regular dish soap, then dry well. It’s important to get all the soap off and dry well. Next soak in regular white vinegar; the vinegar will do a good job of removing the blueing.
I’ve found a few best practices that help.
I use regular white vinegar I buy from the supermarket by the gallon. I pour this into a plastic container. The vinegar cleaning strength isn’t high and does seem to cut through the soap. Note: if you don’t clean or dry it well, you’ll get streaking causing a rainbow effect. This can’t be helped to some degree; you’ll be left with a blue haze that needs to be sanded off; your goal here is to reduce that work.
Another method that comes by way of Dominic Greco is citric acid powder. Dominic cuts and sells spring steel and his own share of plate clean up. He uses a 10% solution of powdered citric acid he buys in bulk on eBay and adds HOT water for maximum efficiency. Footnote: use rubber gloves and for every 10 degrees of temp increase, the effectiveness of the solution increases accordingly. Once it starts to cool, you’ll see it’ll take longer to de-blue the steel. Dominic also offers a number of free handle patterns for those interested in making their own. Check out his site for more info, Two Guys in a Garage. One last note: citric acid is also used when canning so you’ll find it where those supplies are sold.
Ok, back to the plates soaking in the container of vinegar. It’s important the liquid contacts the plate so try not to stack the plates; after a minute or two pull your plate out. I use a maroon medium grit scotch pad to rub it down. You can dunk it again for a little bit, then wipe off. I’ve had some instances where leaving it in too long started turning the plate black so don’t go nuts watching a clock, but be mindful of the time.
Because I do a few plates a month, I pour the vinegar back into a plastic bottle for future use. Next is the fun part; read between the lines, PITA, and for those of you with tennis elbow, something maybe not worth attempting. Sanding the metal plate follows many of the same best practices as sanding wood or anything for that matter. Work clean, don’t skip grades, and above all, apply even pressure. Work smart not hard.
Seems simple enough and it is; the work is just doing it. I normally start with 220 grit, then 320, 400, 600, 800, 1200, and finish with 1500. I’ve been known to go up to 2500 but that’s a lot of work and in the end I don’t find it’s worth the time or cost as sandpaper above 1200 gets pricey. Without getting off topic, I’ll just add that my goal is to try and match the plate to the restoration. If it’s an “all out polish the brass” restoration, then maybe go the extra distance. If you’re more for the au naturel look, then maybe stop round 600.
Just to reiterate about sanding, be mindful of keeping your area clean. I find laying down Kraft paper where I work makes it quick to note when things get dirty. I sand using a homemade wood block with cork applied to one side. With no etch to worry you, block sand both sides. Again, be mindful that the dust from a coarser grit will scratch the plate; watch out when flipping. Lastly, sand in one direction to avoid scratching as you sand. Before finishing with one grit, use a raking light or tilt the plate to the light to check for deeper scratches that need to be removed before switching to the next grit.
So that’s about it on sanding. It’s a skill most of us don’t do well or appreciate enough. I think my first shop class in school was around 5th grade. I had already worked on stuff with my family but I remember in school that sanding was checked before you were allowed to apply finish. You presented the project to be checked and if areas needed work, the teacher would mark an X with pencil. I could do another blog just on the direct correlation of pressure behind that pencil in proportion to the effort put forth; but suffice to say, I still think of elephant tracks and smiley faces whenever I sand something. Taking the time to check your work for marks, going slowly, along with working clean, all go a long way.
At this point you’re now ready to switch out the plate on your saw. I tend to redrill and tooth with the back on but that’s somewhat a personal preference along with installing the back. I’ll save that for another time.
The fastest arm in the East!