HOW TO MAKE A BALSA STROP

NOTE: This is a rough draft and work in progress. Expect errors. Expect typos. The content of this page is the work of @rbscebu and used with permission.

Three balsa strops are required (some make four for a second 0.1μm balsa strop to be used hanging), one for each size of diamond paste; 0.5μm, 0.25μm and 0.1μm. Each balsa strop consists of a piece of balsa wood glued to a substrate. The substrate has two purposes; to prevent the balsa from warping and to protect your delicate manicure while stropping. The over-all balsa strop needs to be reasonably light in weight to reduce fatigue, as it will always be used hand-held.

Three pieces of balsa wood are required, each about 300mm (12”) long by about 75mm (3”) wide. The thickness should be at least 6mm (¼”) (preferred) to 10mm (⅜”) maximum. Anything under 6mm (¼”) will not last as long and over 10mm (⅜”) tends to swell and warp more, even though it is glued to a solid substrate.

Balsa wood can be purchased at most good hobby stores or on line (generally more expensive). You should be able to get one piece 900mm (36”) long by 75mm (3”) or 100mm (4”) wide. You can then cut the balsa to the required 300mm (12”) x 75mm (3”) size with a box cutter and steel-rule guide.

Note: It is a good idea to cut the balsa wood about 3mm (⅛”) bigger (305mm (12⅛”) x 80mm (3⅛”)) and then sand it down to size once all the gluing has been finished and it is set.

Three substrates are required, one for each balsa strop. The substrate needs to be the same size as the balsa wood piece (300mm (12”) x 75mm (3”)), reasonably flat, stiff, light and about 20mm (¾”) to 30mm (1¼”) thick. A substrate of lighter mass will be less fatiguing to use and will enable a lighter pressure being applied when using the 0.1μm balsa strop in the hanging position (more about that later). There are two main popular choices for a substrate; acrylic or composite (ceramic tile on PVC foam or balsa wood).

This must be one piece at least 20mm (¾”) up to 30mm (1¼”) thick. No “manufacturing” is required as it can generally be purchased ready-cut to size (300mm (12”) x 75mm (3”)). Make sure that it is cast acrylic (the most common) and not extruded acrylic that tend to crack more easily. Color of course does not matter. Acrylic can be cut with a jig-saw fitted with a suitable blade. Search the internet for the best way to do this with a jig-saw. If desired, you can “break” the bottom and side corners of the acrylic with sandpaper to make it more comfortable to hold in-hand.

A composite substrate should only be used if you do not have ready access to suitably thick acrylic, or if you want a lighter mass than an acrylic substrate. This is the lightest of substrates but requires the most work to “manufacture”.

For composite you will need:

• A 300mm (12”) x 300mm (12”) x about 6mm (¼”) thick smooth ceramic tile (preferably not with a gloss finish) that needs to be cut into three pieces each 300mm (12”) x 75mm (3”). You can do this yourself if you know how and what to do. A suitable tile is readily available from most home improvement/tile stores or some hardware stores. They may even cut it to size for you.
• If your pieces of tile have a gloss finish, you will need to sand the gloss surface to a reasonably matt finish so that the adhesive will bond to the surface.
• One of:
  • A piece of PVC foam 300mm (12”) x 300mm (12”) x 12mm (½”) to 25mm (1”) thick. You can build the PVC foam thickness up by gluing multiple pieces of PVC foam together. Do not use contact or other solvent based adhesive. The PVC foam can generally be purchased at better hobby stores or on line. Cut the foam with a box cutter and steel rule to form three pieces each 300mm (12”) x 75mm (3”).
    OR
  • A piece of balsa wood 300mm (12”) x 300mm (12”) x 12mm (½”) to 25mm (1”) thick. You can build the balsa thickness up by gluing multiple pieces of balsa wood together with contact adhesive. This balsa wood can generally be purchased at better hobby stores or on line. Cut the balsa wood with a box cutter and steel rule to form three pieces each 300mm (12”) x 75mm (3”).

• Glue to bond the three foam/balsa pieces to the three tile pieces. A structural epoxy glue (not quick-drying) should do. This will be a permanent bond that you should not need to break.
  
  Note: DO NOT use a solvent based glue (e.g., contact adhesive) on PVC foam as it dissolves the PVC foam.
  
• A 25mm (1”) paint brush and about 250ml (½ pint) of acrylic paint (your choice of color). The paint is used to further seal the foam/balsa wood from moisture and it looks better.

To put the composite substrate together:

• If the tile has ridges on its undersurface, you will need to grind these off so that the PVC foam/balsa wood has a reasonably smooth surface to bond to. This grinding can be done with a course (say 400 grit) whetstone.
• Glue a piece of foam/balsa wood to the underside (non-finished side) of a piece of tile. Repeat this with each of the other two pieces of foam/balsa wood and the other two pieces of tile. Allow the glue to set (about 24 hours). Although not required if done properly, you can use weights to hold the bond together while the glue sets – just be careful that the foam and tile remain in alignment.
• Once the glue is set, apply two (or preferably 3) coats of acrylic paint to the foam/balsa wood in accordance with the paint manufacturer’s instructions. Try not to get any paint onto the tile sides or top surface of the tile. If you get paint on the tile’s top surface, remove it with a dishwashing plastic scouring pad once the paint has dried.

You will need a suitable glue to bond the balsa wood for stropping to the substrate. The balsa wood will eventually need replacing once it has been reduced in thickness down to about 2mm to 3mm, so the glue should not be a “permanent” type. It needs to be a type that holds the balsa wood firmly to the substrate (preventing warping), but will later allow you to remove the well-worn balsa wood and such that can be cleaned off your substrate without damaging it. A contact adhesive or rubber type glue works well for this bond. Others may also be suitable. Epoxy glue is not recommended.

Glue a piece of balsa wood to the topside (finished side of tile if composite) to one substrate piece using a contact or rubber type glue. Although not required if done properly, you can use weights to hold the bond together while the glue sets – just be careful that the balsa wood and substrate remain in alignment (not always easy to do).


Repeat this with each of the other two (or three if make a second 0.1μm) pieces of balsa wood and two substrate pieces. Allow the glue to set (about 24 hours).

A completed composite substrate used -balsa strop is shown in Fig. IIA 1. It consists of balsa wood mounted on a piece of ceramic tile mounted on a PVC foam base and painted with acrylic paint.