Refurbishing Grotto Depot: Part 2 – On Brick Chimneys

So in the last installment of the depot renovation I mentioned I was mostly happy with how the chimney was constituted. That’s still true but I thought I might as well show how I make them from sheet. They’re a little fiddly but with the help of a few gadgets from the shop go together in a reasonable amount of time.

Over the years I’ve come to accept that if I want a chimney to look OK I use .010″ sheet for the courses and .005″ for the mortar. Strictly speaking that isn’t the right ratio for the chimneys I’m modelling but both sizes are commonly available and look good enough most of the time.

The job starts out with strip making. I use my calipers to measure down and make a small divot either side of styrene sheet. A quick rub with a pencil helps indicate where the divots are and then a ruler is placed along the top edge of the divots using a drop down magnifying light (3X power). With my left hand holding the ruler I make two quick scores with a sharp knife and then snapped the pieces off checking for final size. Do this several times for either sheet and you’ll be ready for chopping. For Chopping I use a “Chopper” and make a bunch of little squares.

Those little squares will go together one after the other, alternating .005″, .010″, wedding cake style to achieve the chimney we’re after. To make life easier I pre glue as many of them together in .005 plus .010″ pairs. A flat surface with a little solvent seems best to keep them from flying away so I use a bit of steel or glass. Once the pairs are solidified I prick them off with a hobby knife and load them into the fixture shown below. It’s just a bit of bar I milled on the lathe but it helps keep two edges clean and square. These are the reference edges.

IMG_0821 copy

Once dry I clean up any residual out of squareness on the exposed edges with a good fine file. Once square it is time to glue a handle to the base and then make a little brick scribing gauge. The vertical mortar in this case has to be made with small knife cuts and an appropriate width stick of styrene works well enough in determining the individual brick lengths. This is the most difficult part of the operation but going slowly we can avoid a lot of unsightly errors. A few errant cuts here and there can be prodded back together with a knife and additional solvent cement. Follow the knife cuts with either a slightly dull hobby knife or a very thin skrawker. The top of the flue was made out of .010″ styrene strip and glued together as a unit on the steel gluing surface prior to installing on the chimney proper.

With everything glued up and de-burred the chimney is cleaned and readied for painting. I like Tamiya and Vallejo acrylic paints for these sorts of items. There are lots of other choices out there but I like these two because they are available everywhere,easy to use on styrene and I’m not currently sensitized to them. Years in a paint studio and decades of workplace exposure means that I have to take safety precautions wherever I can. I use the Tamiya as a base, first with a dirty mortar colour and then once that was dry and ready brought out the Vallejo to spot the bricks. They seemed very red in the photos I had along with highlights of white  and a bit of umber. I had some similar bricks in my brick collection and used them as a guide along with the photos. Working slightly wet is one of the advantages of Vallejo and provided you use their binder and glazes the bond is decent. I’ve no particular technique – just look at what is there and alter your mark making until you’ve got something that’s works all right. If you’re shaky (I am) use the edge of a desk as a maul stick to support your arms and isolate your movements. As always, use lots of light and magnification.


In the photo above it looks like I need to go back in with the mortar colour and clean up where the brick colour creeped up over the top of the chimney. I need to learn to stay in the lines. Some water lines on the top wouldn’t be out of order either. Incidentally the top of the flue was painted interior first then the red base and finally a lighter red was spotted to hopefully represent a bit of fresh cracking and chipping. This lighter colour is quite opaque and it helped cover any mess left behind from painting the interior. I’ll spray a flat over the works when I’m happy with it.



5 thoughts on “Refurbishing Grotto Depot: Part 2 – On Brick Chimneys

    • Hi Rene’,

      I’m sure there are many easier ways – I just haven’t come across them yet. At this point I’m filing it under the heading of better than what I was doing. As for casting: I’m no fan. If I was making them for someone else then sure, I’d have to be, but I can make them quicker than I can find and operate my casting equipment. That scenario changes if the parts are all the same or similar but so far only two of the chimneys I’ve made are similar in ways that would make casting useful. Machining a proper master and casting fixture also eats up a lot of time and money. They could definitely be printed but I’m only interested in work I can do in-house. It is a judgement call but what I can see as the main failings of the part are down to a lack of dexterity and hand speed. The way to fix that is to do more of the work, rather than less, in my opinion.


  1. Is this in N? It’s very cool work and fiddly enough to be something worth trying out. For your brick courses are you stacking the 0.005″ and 0.010″courses horizontally such that they’d alternate as you moved up the chimney?

    Neat work. I’ll have to give this a try.


    • Yeah,

      The pictures are not very clear but the five thou is a little smaller square and I just centre it up by eye on the larger ten thou square wait twenty minutes and then stack all of the pairs together in the fixture. Before the fixture I used a square but it fell over enough or I needed it elsewhere that I made the fixture. I think I made the five thou squares .020″ smaller on both sides to make positioning them easier. When I have access to a scanner AND the internet I’ll add in a diagram.


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