May 282011
 

Firetacks are a great way to make a night cache.  They are low tech and low maintenance.   The following tutorial will identify some things you should consider when using FireTacks.

The first thing you should do is make sure the area you are placing the FireTacks is accessible at night.  Many municipal parks are closed at dusk.   Look for signs at the trail-head to find the information you need.

FireTack Placement

geocaching firetack placement

Place FireTacks at eye level and avoid viewing obstructions

FireTacks use a retroreflective material.  This means that the  light shown at the firetack will be reflected back to the SOURCE of the light.  For this reason headlamps are recommended.   When using a headlamp your eyes will follow the beam of light.  The FireTacks may not appear as bright to someone standing next to the person with the light.  If you are using handheld flash light hold it to your eye level.    When placing your FireTacks pay attention to the area around the tree you are using.  Are there likely to be trees or bushes that grow up in front of the fire tack you have placed?  FireTacks should be placed at about eye level to minimize the issue of new growth.

FireTack Directionality

firetack placement blind spot

FireTacks have a natural blind spot.

The retroreflective nature of FireTacks combined with the diameter of the tree they are placed on create a natural blind spot behind the FireTack.   It is important to remember this when placing FireTacks in the bush.  The searcher can follow the FireTacks in to the cache but what do they follow to be back to the trail?   It is very easy to get turned around in dense foliage when searching for a cache.   If you are using flat trail reflectors you should place one on each side of the tree.  One for the way in and one for the way out.  This safety procedure means you will need more markers if you are using flat reflectors.

firetack placement egress

FireTack Placement for egress

With FireTack reflective trail markers you can place the marker perpendicular to the direction of travel.  In this way you can see the same reflector on the way in and on the way out.   When placing a complicated cache it is always a good idea to have someone test your geocache placement before it is published.   I have had to amend several cache placements based on tester feedback.  Keep in mind there is still a blind spot behind the FireTack.  If your path to the cache turns you may have to augment your egress path with additional FireTacks.

Variation One – Counting FireTacks

firetack counting

Count the number of FireTacks

There is more than one way to lay out a FireTack trail.  The most common is just lay out the FireTacks exactly where you want to lead the cacher.   A slight variation on this type of cache is where you count the number of FireTacks you see and at a certain number you turn or do something different.   Another way to  approach this type of cache is have the cacher go until there are no more FireTacks and then count back a small number.  At that point is where the cacher turns in.

In this example the cache location is marked by a different color FireTack.  You can use colors to mean different things.

The fact that you aren’t sure where you are going or if you’ve seen all the FireTacks makes this kind of night cache fun.  There is something about feeling a little lost in the woods, at night, that heightens the excitement.

Variation Two – Pattern Change

firetacks pattern change

Pattern change signals direction change

An alternative to making geocachers count FireTacks which is not as easy as it sounds.  Night Caching in the rain or the winter tends to inhibit one’s ability to accurately take notes.   Using a pattern change is a good way to tell cachers that you expect them to do something different.

As with the previous example extending the FireTacks past the turn off point adds a little more complexity to the cache, from the searcher’s point of view.

How far apart should you place your FireTacks?  There is no easy answer for this.  FireTacks are visible from hundreds of meters when using a bright LED light.    In practice the effective distance is much lower because of obstructions.  Trees, branches and leaves all play a part in making your FireTacks harder to see.   You should place the reflectors far enough apart that the searcher has to be on the look out for them but not so far apart that a small branch will obscure the view.   In the real use you can expect to place FireTacks every 40-80 meters.  This is another example of why having someone that didn’t help you place the FireTacks should test your cache before it is published.  Feedback from the trial will allow you to add more reflectors if required.

Variation Three – Color Change

firetacks color change

Change in reflector color indicates a direction change

You can take advantage of the fact that FireTacks come in multiple colors to introduce some complexity into your reflector trail.  Different colors may mean change in direction (that might include looking behind you),

You could also create two paths using different colored FireTacks.  One path could be a red herring and the other is the target path.  Adding a color hint to the cache description would let the cacher know which path to take.

The examples provided in this tutorial are a starting point.  Expand on these ideas to create a unique cache that other geocachers will enjoy finding.

Firetacks are made of durable materials and will work for many years.  Mother Nature has a way of reclaiming her turf and some firetacks will go missing.  While FireTacks are a low maintenance way to build a night cache you should expect to replace about 10% of the FireTacks each year.

Mar 152011
 

 

FireTack colors

Why are FireTacks so bright? The short answer is that they are retroreflective. Retroreflective means that much of the light shown at an object will be reflected back to the source.  You most frequently see this effect on road signs. These signs are designed to be visible from distances sufficient for the sign to be helpful. Stops signs you can’t see until it’s too late are not helpful.

In every day circumstances most objects we see are either diffuse reflective of mirror reflective.

In mirror reflective materials the light is often directed away from the viewer. In this way these materials do not always appear bright to person holding the light source.  The same cannot be said for the person viewing the reflection! Shiny or mirror like objects may seem like a good choice for building a night cache but generally they are not.   There are more useful for creating effects that would make an night cache interesting but they do not work well as trail markers.

Diffuse reflection is what you get from something like snow or a white sheet of paper. The return path of the light source is spread out in many directions. In this situations the object will appear bright from a variety of angles but not much light is sent back to the viewer. We percieve these objects as being brighter than their surroundings but they aren’t necessarily very bright at all.  These kinds of materials are best suited for increasing contrast between objects during the day.  Increased contrast is helpful at night if you are trying to make it easier for the cacher to distinguish writing or shapes that make up part of your night cache.

Retroreflective materials in contrast can return as much as 58% of the light to the original source.This is why retroreflective materials are visible from great distances. There is one draw back to retroreflective materials and that is that they have a very small effective observation angle. This is the angle between the light source and your eyes. Typically for the observer to notice the retroreflected light their observation angle must be less than 1°. In most cases an observation angle over 2° renders the FireTack ineffective. FireTacks are effective when holding your flashlight slightly above your your head or no more than six inches below your eys.  Make it easier on yourself and use a headlamps when following FireTacks. The retroreflective nature of FireTacks make them the best choice for trail markers.  (Remember to use them for the trail out as well as the trail in, use different colors to distinguish the inbound and outbound trails.)

Flat trail markers are visible to the observer from head on or slightly to the side, around 60° either side of head on. By making FireTacks three dimensional there are more surfaces thus increasing the available viewing angles.  As a result the observer has a better chance of seeing the trail.

The type of material used in the reflective trail marker also influences its brightness. FireTack brand trail markers use ASTM type VI and above materials while other brands use ASTM type II materials. The material used in FireTacks has 1000 prisms or glass beads impregnated in the material per sq. inch.  The material material used in FireTacks is highly flexible, withstands impact,  severe hot and cold, is guaranteed to maintain up to 75% reflectivity for ten years or more, even when left outside for the whole ten years.

Note: FireTacks is the brand name of reflective trail markers from WildTech Corporation.