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Track Construction-Part 3 Painting and Laying the Braid / Tape

Page updated April 2007

Track Construction Part 1 described how to build the surface of the track. Track Construction Part 2 talked about the choice between tape and braid - you have to decide which at the cutting stage so you can cut the recess for braid (or not).

It is best to finish the carpentry before painting - and taping/braiding. Some cutting of the track surface is usually necessary for lap counters - either to produce an isolated pick up section or to insert optical detectors in the slot.  When building a braided track its probably better to paint the surface first, then lay the braid. For taped tracks the tapes are often laid first, then the surface is painted, although you can paint first then tape if you prefer. The lane colours should painted on after the surface painting and braiding/ taping are complete. 

Lap Counter Position

Lap counters (and hence the start line) should always be where there is a minimum risk of counting errors. Generally lap counters work most reliably when the car is firmly in its own slot. Obviously it is possible for a car to be in the wrong lane on any part of the track, but on some parts of the track it will be relatively easy to observe which wrong lane it was in (and correct the scores).

The best place for the counters is usually at a medium speed position on a flat straight. Avoid places where the cars are likely to fall out, (e.g. corners) because you won't be sure if the car left the slot just before or just after the counters. Avoid places where the cars are likely to be up on two wheels (e.g. corners and just after corners) because the guide may be partially out of the slot. Avoid places where the guide may be lifting out of the slot (e.g. the top of hills, just after the top of hills, immediately after track joints, where cars will be on full acceleration from very low speed corners, or very high speed parts of straights). Lap counters will be covered in Part 4 of this series.

Painting the Track Surface

The track surface needs to be painted with smooth paint between the conductors. I recommend smooth paint even if you will be running Scalextric hard (not sponge) tyres. These hard tyres will grip well on a smooth surface, masonry paint may produce slightly more grip when it is new, but the grip goes off fairly quickly and tyre wear is much higher. The ideal finish is matt, a perfect "mirror finish" gloss isn't desirable. Some fairly robust paint such as polyurethane is good. Some builders now favor floor paints, the slightly rubberized texture can work well.  The colour is a matter of personal taste - I've seen several tracks in anything from black to off white , some shade of grey is most common - and looks reasonably near to the colour of a real road.

To paint under the braid/tape (or not?)

Do you paint where the tape/braid will go, or stick the tape/braid direct to the board?  I've seen very satisfactory results with either method. 
Adhesives will stick the tape/braid to the bare board pretty well - sometimes too well for the well being of the board !  Are you thinking of sticking the tape/braid to a painted surface? It is important to check that the glue you are using is compatible with the paint - some combinations of paint and adhesive don't bond properly so I'd recommend doing a small test piece first.  

Perhaps I should explain further......
In most cases, when first applied, the adhesive bond to bare board will be stronger than the bond to a painted surface. At first you'd think that a stronger bond is better - that's true if the the tape or braid never needs to be replaced.  Yes but.....  the tape or braid sometimes does need to be replaced, and when it does you don't want it to come away without damaging the underlying board.  The braid recess is normally deep enough to remove the hard outer surface of the board and expose the softer inner layers of the chipboard or MDF.  There are considerable variations between boards.  With chipboard the internal particles may not be that well bonded together, so trying to remove freshly laid braid can pull particles of board away from the surface of the recess.  With MDF the internal layers may not be that well bonded together, so trying to remove freshly laid braid can pull a paper thin layer of board away from the surface of the recess (and a paper thin layer really doesn't matter) or cause several layer to delaminate (which does matter!). Several layers delaminating is a feature of less dense / lower quality MDF. Painting the recess may help a little in sticking the board together, and may reduce the adhesive bond strength so that when trying to remove freshly laid braid the adhesive bond fails before it rips the board apart.  

Over time the adhesive bond is weakened, the use of solvents for track cleaning is one of the main reasons it weakens.  When this happens the bond between the tape/braid fails first, and a layer of adhesive remains on the track.  Thus old  tape/braid is most unlikely to be stuck down well enough for it's removal to do any harm to the underlying chipboard/MDF.

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Above - An example of braid removed from track after about 2 years in use where the surface braid recess was not painted.  This track used good quality MDF, and a paper thin layer of MDF has come away with the braid.  Note that the majority of the recess is covered in the old glue (darker colour than the MDF) which will need to be removed prior to laying the new braid.

To summarize - Assuming the glues and paint are compatible, painting the braid recess sounds like a good idea unless you've got really good quality board. With really good quality board. There's probably some advantage in not painting under the braid.  It's probably better not to paint under tape.

 Applying the paint

Paint can be applied by brush, roller or spray.  The paint needs to be kept off the area where the braid / tape will stick (if you are painting first). The paint needs to be kept off the tape (if you are taping first). Brush painting does not require any masking, spray painting most definitely requires masking and rollers probably need masking. I leave you to decide if the extra time spent masking the braid recess or tapes is worth the time saved by not having to carefully brush paint all those edges. I’m assuming that any club with enough DIY skill to do the carpentry on a track will have plenty of experience of painting wood properly, so a full description is not necessary.

Tracks have to tolerate considerable changes in humidity, particularly as many tracks are housed in unheated rooms. This has led clubs to think about the best way to protect their tracks. Some clubs varnish/ paint the underside of their tracks to seal them.  Tracks do tend to distort with age, some would say it is possible sealing the underside may reduce this.  Some unsealed tracks show no signs of problems - short of having two tracks one sealed and one not in the same clubroom for some years it is difficult to know how to be certain if sealing the underside makes a significant difference.

I have been asked about painting the slot. I have seen each slot painted in the lane colour, and this is an interesting alternative to the normal stripe alongside the tape. Slots are sometimes  painted just for sealing. There are tracks over 30 years old which do not seem to have suffered from not having the slot sealed.

Laying the Tape or Braid

The conductors (tape or braid) should be stuck to the track using an impact adhesive such as 3M Fastbond 10 or Evo Stick. I found a litre of Fastbond 10 was plenty for a 4 lane track with 107 ft. (33 m.) lap length, so don’t buy a 5 litre tin unless you’ve got a use for the rest of it!  Always read the instructions and observe the safety precautions! Adhesives work best on clean, grease free surface.  OK, there's rarely much oil or grease on MDF, but there may well be some lubricant left over from the manufacturing process on the braid.  Ideally you should  remove any traces of oil of grease from the braid with a suitable solvent (yes I know people often don't bother, but it can help your braid to stay stuck down a bit longer).    There is certain to be a lot of dust generated by cutting MDF, so make sure you remove loose bits and dust (preferably with a vacuum cleaner) before trying to stick anything. This advice is doubly important in repairs where the old adhesive needs to be removed first. If you buy Evostick in tubes, apply it straight out of the tube. Adhesive from tins needs to be decanted into a squezable plastic bottle with a small nozzle (an old well cleaned goop bottle is fine). Once out of the tin the adhesive soon dries up in a plastic bottle, so if you are not going to use it in the next quarter of an hour, put your "goop" bottle inside a screw top glass jar to keep the solvent in. Incidentally if you think this use of old goop bottles is a bit crude and the professionals must have a better way, Steve Ogilvie tells me he uses an old squeeze mustard bottle for this job!

Applying adhesive ready for braid	Tape (left) and Braid - both about 6mm wide

A good way to apply glue to braid is shown in the diagram above right. This is a technique Hasse Nilsson was shown at Southend (Wonderland Raceway) about 30 years ago and he‘s used it ever since. Here’s how it works – Staple the braid to a cardboard cylinder at one end. Wind the braid round the cylinder so the edges are just touching. Staple the other end of the braid to the tube. Coat the braid with contact adhesive using a paint brush. When dry, remove the staple at one end and it’s ready to lay. 

Below - a picture of this technique in use on the BSCRA "UK8" track - Hasse Nilsson (right) is laying braid (on the hottest week end on record).

Avoid ancient tins or tubes of adhesive - it doesn't work as well when it's well past is sell by date or when its been opened too often. Adhesive spreads better when its not too thick; braid is more robust if the adhesive runs in between the strands and holds them together. With press on tin lids, one way to reduce the risk of the contents setting in the tin is to stand on the lid to make sure its shut, the turn it upside down to make sure the lid seals before storing it right way up. While we are talking about impact adhesives - the bond will fail if its immersed in solvents such as lighter fuel or white spirit. So go easy on the solvent when cleaning the tapes!

Apply the adhesive and spread it to an even film to both surfaces - always apply the adhesive the board second (its much more porous than metal so the adhesive dries quicker.) When the adhesive is touch dry press the conductor onto the track.

Tape - Tape needs to be pulled tight as it is put down, so that it is in tension when its laid. Press the tape hard down onto the track, a piece of wood is good for pressing the tape down.  (An offcut 10-20cm long will do fine)  You can press the tape down with your finger but there is a risk of cutting your finger on the edge of the tape.  Also you can press harder with a bit of wood and pressing harder is better.      The whole point of this is to ensure the tape is in tension so it is less likely to come up with temperature / humidity changes if the adhesive bond fails locally. There is no point in pulling it beyond the point where the tape is permanently stretch, as this will not increase the tension in the tape, simply make it longer and thinner. It can easily be stretched enough to follow tight radius corners without crinkling - obviously on a  bend the outside of the tape is stretched more than the inside.   Copper isn't a very good spring material, and with time the tension will relax. If a tape is repaired after a couple of years it will be found to have lost all tension - although this does mean it that if its just come unstuck (and is undamaged) it can be relayed under tension, and there will be enough overlap to make a decent soldered joint.

Braid - Braid  (unlike tape)  is not under tension once laid - the braid just settles at where its put. It is easier to lay braid accurately because there is a recess in the track which defines its position.  The amount of tension applied during laying can be adjusted to get an even top surface.  Where braid goes down under the track it usually needs pulling hard to prevent a bump. In the middle of lengths it often needs hardly any tension, in fact if you pull too hard the braid and get noticeably narrower.  Always keep he braid to the side of the recess away from the slot. Braid can be pulled up by contact with the guide when a car deslots, braids last longer if they are (A) well glued down on the edge nearest the slot and (B) there is a slight gap between edge of the slot and the start of the braid.  At the risk of stating the obvious, this is particularly important on the outside braid in a corner.

In either case make sure the conductor is well pressed down into place after its laid. Its advisable to go over a freshly laid length of conductor several times to ensure it is pressed down fully.

Feeding in the Power

At the end of sections take the end of the tape or braid down underneath the track as shown in diagram N. The power can conveniently be connected here. 

Where the track doesn't come apart in sections, rout a sideways slot to take the conductor underneath the track. Lengths of tape can be joined by overlapping and soldering (the extra thickness off tape is small enough not to be a problem) The most satisfactory way to join braid is to route a sideways slot (see diagram O) and take the ends under the track.

Magnetic braid and other methods of providing magnet traction are covered in a separate section.

The wiring is covered in part 5 of this series.

For marshalling purposes it is essential to clearly mark the lanes so that the marshals know which lane a car goes in. If its easy for the marshal to identify the lanes there will be a lower risk of mistakes - and that's good news for everybody! (I could also mention painting your cars so as not to camouflage the lane stickers - but that's really a subject for another article.) There are two ways of identifying lanes - colour is almost universal on club tracks - but you can use numbers. I’ve only ever seen numbers used on 8 lane tracks, but you could use them on other tracks. Lane stickers are the club’s responsibility - the standard ways of doing it are:-

The lane colours or numbers are added once the surface is painted, If you are building an eight lane track there is a standard colour sequence as shown in the table - don't go confusing everybody by doing something different!

 There is no standardisation in four lane tracks. It pays to give some thought to the lane colours. PVC tape for lane stickers is usually available in red, blue, yellow, green, black and white, so choose from these colours. Make sure the colour stands out from the track surface - don't use black on a black track! It can improve recognition slightly to have alternate light and dark colours, and in some circumstances blue and green can be confused. The colour should ideally be painted in a continuous stripe. This is usually done with a stripe alongside the conductor - a pin striping tool is the best way to do this. Another approach is to paint the slot lane colour. Shorter paint markings can be used, although if there is too much of a gap between them, this can cause a slight delay while the marshal works out which lane is yours!

Lane numbers are painted on to the track surface in appropriate places. Obviously they should be in contrasting colours - white on a dark track, black on a light one. The numbers are usually about 25mm (1 inch) high. A stencil is needed to do a decent looking job (Even if somebody can do concourse standard hand painted numbers they are likely to get bored after a couple of corners and it’ll look a bit of a mess by the end of the lap!) The numbers need to be in all the places where cars may have to be marshaled - this is a lot of number painting if you are going to avoid marshalling delays while the marshal searches along the track for a lane number.

Chris Frost