Bricking a W.F. Mason Evaporator

Call me crazy, but I could have sworn the forecast for today was for some left over drizzle early in the morning followed by clearing and warm temperatures, like mid 40’s, with Sunday possibly reaching 50F…

Well, as always in New England, the weather did what it wanted to do and not what I wanted it to do!  Given the early forecasts, I had planned to install the 1” arch board, and start the process of cutting and installing the fire bricks into my W.F. Mason 2×3 Hobby Evaporator.  The arch board can be cut with hand tools, but for the fire brick I was planning on cutting them with a tile wet saw.  To do this I needed to have the saw outside and needed to keep it fed with water to aid in cutting and dust control.  All of which needs temperatures above freezing.  The chilly weather and lack of sunshine made for some might cold and wet fingers!  Luckily, I had my iced Dunkin’s coffee nearby to help take the edge off.

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For the last two weeks, I have been researching and planning the bricking of the evaporator out in my head.  The Maple Trader website and it’s Community have been an invaluable resource!  For example s fellow maple addict, Steve from Vermont Rustic Moose, has been a great help!  He happens to have the same evaporator that I have and has provided me with countless tips and advice based on his experiences with his W.F. Mason 2×3 Hobby Evaporator.

Now there is some good bricking information on Bill Mason’s website with some great photos and even a power point presentation, but they are for a slightly larger arch (2×4) that has a slightly different fire-box configuration.  To complicate matters further, I also wanted to add some arch board, which should help insulate the arch keeping more of the heat in the firebox to heat the syrup pans.  As an added bonus the arch board should also keep the outside of the fire box cooler.

So what is this mysterious arch board?  Last week I picked up eight pieces of this 1” thick x 12” wide, x 36” long fiber board material at Bascom’s Maple Farm.  It’s firm to the touch, but you can easily dent it with finger pressure.  It’s not cheap, coming in at $9.75/EA, but it’s a safety thing, and makes me feel more comfortable working around the arch, especially if the boys are near by, and you know they will be.  Fortunately, the arch board contains no asbestos, however it still has silica and is fibrous, so it can be irritating/hazardous if your making a lot of dust.  If cutting with a saw a dust mask and safety glasses should be used.

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I started cutting the arch board with a utility knife and quickly found that the utility knife was not the best tool to use.  With the board 1” thick a utility knife goes about half way through it, this requires you to cut the board from both sides and it takes more time.  After cutting two pieces like this I figured I needed find a better tool, and in my collection, I came across this little beauty from Veritas.  It’s Veritas’s Flush Cut Trim Saw, and I had purchased it many years ago, to flush cut some dowel plugs on a woodworking project.  This little tool in conjunction with my utility knife used for marking and scoring were the best tools to use for this material.

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This project took a lot of thought and I just took my time starting at the bottom and the front of the evaporator, I laid out arch board and bricks multiple times to mock-up the installation.  I felt that this would make the most efficient use of my materials and allowed me to plan out my next steps prior to cutting too much material.

Step 1, The First Cuts – I knew I wanted to have a solid fire brick (aka split) on the edge of the ash grate to help protect the arch board that I would be laying on the bottom of the fire box, so that is where I started my installation.

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Step 2 – I cut the fire brick (aka splits) in half using a tile tub/wet saw that I had borrowed from a friend.  The tile saw is the only way to go as far as I am concerned when bricking an evaporator with splits (1-1/4”x4-1/2”x9”).  Cutting the splits in half made them only slightly shorter than the thickness of the 1” arch board and a split combined and laid horizontally, so I cut the bricks in half and surrounded the perimeter of the ash grate with the splits.   They ended up being about 2-3/16” tall.  I then surrounded the splits that I stood on edge with a layer of arch board laid on the flat.  Next, I mocked up some arch board on the sides to get a feel for how I was going to lay out the front and sides of the arch.  Because I am not cementing the splits in place this season I needed to pay attention to how I laid out the bricks so if I bump the evaporator, I don’t have loose bricks falling into the firebox.  The sides of the 2×3 Hobby Evaporator slope out so I have gravity helping hold the bricks on the sides, but for the front and the back, which are vertical, I needed to be a little crafty.  So, to help lock the front in, I needed to board & brick the front prior to the sides.

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Step 3 – The Front may seem complicated, because of the the various angle irons that are welded on for the door, the angled sides, and the door opening itself, but its not as bad as you think.  This was my third piece to cut out of the arch board and it is also when I went looking for a better tool to cut the arch board.  I measured the top of the arch and it happened to be 24” wide, which is perfect for two pieces of 12” wide arch board.  With this information, I cut the first piece of arch board to length and then I cut the angle for the side which slopes inward.  The bottom of the arch front measures 20” wide ,so I laid out the angle cut 2” in from the edge which is half of the 4” difference in width.  I then pressed the arch board into the front of the evaporator so that the metal angles would leave an impression on the back of the arch board.

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I then traced the pattern of the angle irons with a pencil allowing for a little extra room, maybe no more than 1/16”, so it would fit easier the first time I tried to install it.

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Next, I cut along the lines doing the left and right sides in the photo below first, followed by the long bottom cut.  I was able to saw my way into the middle of the arch board by using the Veritas saw at a low angle, almost flat, and than slowly angling the saw until vertical when you reach the limits of the cut on each side.  Finally, I sawed in the little notches doing both sides first and finishing the small horizontal cuts by plunging in my utility knife once on both sides of the board.  With half of the front cut I was ready to test fit, fine tune, and install it.

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The photo below shows a better view of how I made the impression of the angle irons into the arch board.

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Step 4 Finishing the Bottom – With the front complete, I needed to finish the bottom or floor of the arch, in order to do the back.  Because I am experimenting with stepping up the back of the arch, I decided to line the floor of my arch towards the back even though I would be adding another layer of arch board in a later step.  The bottom is easy, two more pieces of arch board and it’s onto the back.

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Step 5 The Back – the back was a cake walk, simply repeating the same process for the front.  I divided the back into two 12” wide pieces, cut the angle for the side, set it in place, and traced the outline for the flue/stack with a pencil on the back.  I then used a coping saw to cut the curves starting at the top of the circle and cutting until I bottomed out the coping saw and then cutting at the bottom of the circle until I bottomed out the saw there as well.  This left about a 1” long segment of the circle, right in the middle that I had to cut with the utility knife.  It’s a straight forward cut and just requires you to make the cut from both sides with the utility knife.

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Step 6 – The Sides are easy.  I did lay them out with a narrow piece of arch board on the bottom so that when I lay my first course of fire bricks the horizontal joint in the arch board will be overlapped by the bricks.  I used almost a full piece of arch board for the top of each side.  I believe they measured 12” x 34-1/2”.

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I can’t stress the importance of mocking up your brick arch board as you progress through the installation. I spent a fair amount of time laying up full bricks to get a feel for how I wanted to install everything.  This cost me a lot of time, but kept me form having to cut and re-cut, and kept me from wasting any materials due to error.  Keep in mind that this is all being installed with no plans or instructions.

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Finishing the sides with arch board wrapped up all the easy cutting.  From here on out it’s the tile saw, and cutting fire bricks.

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After mocking up some brick layout below it was time to cut!  As with the arch board I started from the front and bottom and worked my way to the top and back.  The fire brick or splits as mine are often referred to are 1-1/4” thick, 4-1/2” wide and 9” long.  They line the arch and protect the fibrous arch board from damage from loading wood.  They are like a light weight version of a brick but are made with specific materials to withstand the high temperatures of a wood stove or evaporator.

The tile saw – I was fortunate enough to be able to borrow a pretty decent tile saw that cut the bricks easily.  Like with any tool that I own, I took my time and went slow.  It’s important to go slowly and let the diamond blade due the work of cutting the brick.

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I pretty much cut bricks as I went.  Starting at the front with a couple angled cuts I was able to start the sides.  The sides are installed using running bond, and everything is dry fit and held in place with gravity, and other adjacent bricks.  I will be boiling outside (no sugar shack) so I need to move the evaporator inside after the season is over.  To do this I need to be able to lift the evaporator which means taking the bricks out at the end of the season.  This required me to think a little more about how to hold the bricks in place without using fire cement.  I spent a fair amount of time mocking up and laying out the bricks to accomplish this.

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A dwindling pile of fire bricks.

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Towards 4:00PM Saturday I had reached a good stopping point and had to catch up on some other chores around the house.  I had bricked the front, back, sides, and the lower portion of the floor of the evaporator where the wood fire will be by the ash grate.  Towards the back I am in the process of laying out the step which will help keep the flames and or hot exhaust gases up towards the bottom of my syrup pans, in theory of course.  I spent about 7-hours Saturday and probably have another couple hours Sunday to complete the bricking.

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This has been an intense process, but very fun.  Almost like building your own jig saw puzzle.  I am glad I am doing this now and not when the sap is flowing!


So, I have to admit I was a little sore yesterday.  There was a lot of crouching and bending over the arch to insert and take away bricks and I sure felt some stiffness in the morning and the fact that the weather was still miserable out didn’t help motivate me.  The temperature was a mild 40F, but still felt cool and damp with a heavy fog and was just an overall dreary day.

After I completed my Sunday chores it was time to complicate the install of the step in the back of the arch a little bit.  Essentially, I built a raised platform on top of the arch board that was lining the bottom of the evaporator.  It may have been easier just to stack bricks to fill the space but that would be too easy.

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Once I more or less built the perimeter frame and leading edge I was ready to install a layer of arch board on top of the frame work of bricks.  I had some extra arch board and needed the extra 1” of height, so in it went.

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The finish line is nearing!  Only six more bricks to install and because I like symmetry I needed to cut each one to length.  I could have just put three full size bricks on the step and only cut the other three to length but than the design would not be balanced!  After all, what is three more cuts and what would I do if a visually unbalanced brick layout some how screwed up this years syrup making!  To be safe I chose symmetry and a few more cuts.

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As I placed the last brick, I was not quite finished.  I still needed to completely unbrick the arch so I could move it to the yard.  At first I thought I would be able to only take some of the bricks out, but then I tried to move this pig fully loaded and she was not going anywhere!  I guess 56 bricks is a significant amount of weight when you put into a big metal box and try to move it all at once!

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It took all of my inner strength not to fit these bricks super tight for no gaps, but from what I read I need to allow some space between the bricks so I can cement them in at a later date.  Now to take it all apart move it to the yard and level it up.

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Hopefully six weeks from now, when I go to disassemble the arch for summer storage this blog will help me remember how everything goes back together!

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Leveling her up before I re-brick her…

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Not too shabby.  I probably should have used metal washers to shim her up, but all I had on hand was wood shims.  Next year perhaps.  With the syrup pan level, I brought the pan back into the house and started re-bricking the arch.  I covered the arch up and I am ready to start thinking about the stack next.

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