Ballasting/Underlay

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Ballasting 1
Ballasting 2

Ballasting/Underlay

This section is dedicated to the methods used to imitate ballast. These methods include both granular ballast usually made from finely crushed natural or imitation rock and underlay rolls that have many forms including foam, granular ballast covered foam and scenic rolls with a ballast surface. Granular methods are usually referred to as ballast whereas sheet or rolls are usually referred to as underlay. Granular methods are more successful when a cork or dense foam sheet or strip underlay is used as a cover material over the timber baseboard surface to act as a sound damper and to raise the track off the baseboard to give the ballast profile.

Underlay or Ballast?
 

Underlay is a more simple method of representing ballast that allows the enthusiast to alter their track plan without damage to the track. Ballast is a permanent more realistic method of fixing the track to the board bonding the ballast to the baseboard or sheet underlay (cork or foam). Ballasting should only be used when working to a track plan as once the ballast has dried the track cannot be lifted without damage.

Ballast Underlays

Ballast Underlay is a quick method to visually represent ballast and include foam rolls and scatter material sheet ballast. The most popular foam underlay is manufactured by Peco where a range of profiles for the Peco range of OO and N gauge Setrack and Streamline turnouts and crossings is available. Hornby offer a similar product as an underlay roll but turnout profiles are not available, only flat foam sheets. The foam underlay is usually stuck to the track using UHU or similar adhesives but not stuck to the baseboard. A track pin is then used to fix the track and underlay to the baseboard allowing the track plan to be altered without damage to the track or underlay. Foam underlay degrades with time and is not suitable for use on long term projects. 

Gaugemaster and other manufactures produce a foam roll underlay that has a granular ballast adhered to it making it more realistic than foam ballast and helps to protect the foam from degrading. This underlay however is not available in profiles manufactured to the shape of turnouts and crossings and therefore requires cutting to shape accordingly. If time is taken to install the ballast underlay carefully a good finish can be achieved as shown in the images below. 

Ballast

Ballasting is a skill that requires great patience as care must be taken to prevent poor running and damage to the track. A neat finish requires many hours of dedication returning to the ballasted area several times as the adhesive dries to ensure a tidy finish. Airbrushing a general grime over the ballast improves its appearance, emphasising areas where grime would accumulate, or where oil would be deposited from standing locomotives. Never use just one ballast colour as this tends to look poor on a layout, try and blend a few colours if possible or buy a mix e.g. Woodland Scenics Grey Blend. Be careful of the cheaper granite ballasts, they tend to 'green' once adhesive is used. Use a quality ballast e.g. Woodland Scenics for improved grain size (fine for N gauge, medium for H0/00 and coarse for 0) and excellent colour stability. 

A good quality sheet or strip underlay should be used beneath the track to act as a sound damper and to visually represent the ballast profile. The most appropriate materials for this purpose are sheet cork or dense foam.

Once ballasted the appearance of your layout can be improved by weathering your track and ballast as shown in the image below. Please see our TRACK & BALLAST WEATHERING section for more information.

It is usually a good idea to complete your platforms before you finish ballasting to allow a neat finish. For some useful tips on platform construction please click here PLATFORMS.

The best methods of applying ballast is to use one of the techniques below. Always try a sample to perfect you technique.

bulletMain Method - This is the best method to achieve the neatest finish, but also in the minimum time. As you lay the ballast at the same time as the track, it makes track laying a longer process. Mark the location of your track on the sheet underlay and drill any required holes for turnout motors or similar. When marking the track location, mark the extent of the ballast shoulder if this is not limited by the edge of the sheet underlay. Brush away any debris from the area. Using a slightly diluted PVA mix cover the area to be ballasted - ensure all turnout tie bars or similar are left free of adhesive. It is not recommended to attempt to cover areas much greater or equivalent to four tracks wide and a metre long - if your PVA dries quickly this may be too much so start with a small area. Place the track back into its correct location, and if required pin or use drawing pins to hold in place. Next cover the whole area with ballast up to at least sleeper depth. Leave over night to dry and then vacuum clean away the remainder that has not stuck. A neat ballast finish will be left!

View step by step images of ballasting using this method.

Ballast applied to PVA adhesive as the track is installed. The adhesive remains at a depth below the level of the top of the sleeper but the ballast is poured on to the top of the rail.

The same layout installed with the excess ballast removed by a vacuum cleaner. Use a clean bag less vacuum cleaner to allow the excess to be reused.
 
bulletCascamite method - Cascamite is a white dry powder adhesive which is mixed dry on a ratio of approximately one part Cascamite to three/four parts ballast. Lay the dry mix onto the track and dry brush in place as neat and clean as possible. When the dry mix is in place, use a 'greenhouse' hand spray with water and a drop of delineated alcohol or washing up liquid (this breaks down the surface tension of the adhesive) to spray the dry mix until saturated. Always spray over the ballast not directly at, as the blast will spread the ballast. Return to the area and tidy as the ballast dries. Once the ballast has been sprayed, the following technique can be used on the wet ballast.
bulletPVA method - PVA must be one of the most versatile and useful adhesives invented. Ballasting is simple but no quicker using PVA. Dry brush your ballast in place as neatly as possible. Using a water spray as described above (with the same contents), saturate the ballast before applying any adhesive. Mix PVA with water until it can be picked up by an eye dropper or pipette (at least ten parts water to one part PVA with alcohol/washing up liquid as above), drop the dilute PVA onto the wet ballast and watch it soak through. Continue applying until the mix reaches the base of the ballast. This can be observed by eye. Spray with water mix as above if required to spread the glue. When ballasting large areas, we use a washing up liquid bottle filled with the dilute PVA mix! The mix is not critical, if too thick on a trial piece, add water; if too thin, add PVA.

          View step by step images of ballasting using this method.

Once the ballast is in place, lightly airbrush a track grime over the whole ballast area with heavier applications where more dirt may accumulate as described above. Once the grime is dry, weather the rail faces with a rust paint and allow to try completely before cleaning.

Professional Layout Service offer a ballasting service when laying track. We will also ballast and airbrush your existing track and rust the rail faces.

 

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