What is Epoxy ?
Sources of information about Epoxy
Using Epoxy on a Lugger
How much to buy?
How to use Epoxy
Step by step guide for mixing
Materials & equipment
Measuring out the Resin
Measuring out the Hardner
Stirring the resin/hardner mixture
Using the Resin

What is Epoxy ?

Epoxy resin is an exceedingly versatile plastic. It is supplied as a liquid in two containers: one holds the resin whilst the other holds the liquid hardner. When the two are mixed in the correct proportions a chemical reaction takes place and the mixture 'cures' to form a hard tough transparent plastic. Whilst in the form of a liquid the Epoxy can be applied to wood to form an exceptionally tough waterproof coating. In combination with glass fibre it makes a super strong glass reinforced plastic laminate (i.e. fibreglass). With addition of the appropriate powder it can be used as a filler or an extremely strong adhesive. It bonds equally well to wood, metals (including stainless steel) and polyester-based GRP. It is used extensively in the construction and repair of most high-performance sailing boats and is an excellent resource for wooden or GRP boat maintenance.

Sources of information about Epoxy

In the projects described on this web site I have used West Epoxy Resin (WEST is an acronym for Wood Epoxy Saturation Techniques). I can recommend visiting the relevant web sites which contain much more detailed information than given here and also include lists of suppliers world-wide.

Select this link to go to the website reference section on West Epoxy.

Additionally each pack of resin contains an instruction sheet.

Using Epoxy on a Lugger

Epoxy resin can be used for:

• Coating the spars. No need to thin the first coats. Three coats provide a thick, tough coating much thicker and more resistant to abrasion than conventional varnish. However, the cured resin is attacked by the UV component of sunlight and should be overcoated with 3-4 coats of conventional varnish containing a UV blocking compound. Note that it is not suitable for coating teak because the natural oiliness of that wood prevents the epoxy from making a proper bond.
  
  
• Additives in the form of specially formulated powders can be stirred into the epoxy for special uses. One of these forms a strong adhesive for bonding wood, GRP, stainless steel and other metals in any combination: excellent for repairing split spars or for re-lining screw holes where screws will no longer hold in worn/rotten wood.
  
  
• Another powder additive makes a superb filler which is suitable for overcoating with gelcoat, paint etc.
  
  

How Much to Buy?

For most purposes a 1.2 Kg pack (consisting of 1.0 Kg of 105 Resin & 0.2 Kg of 205 Hardner)will be adequate and will suffice for several projects. Currently this costs around 23 UK pounds.

How to use Epoxy

General points for guidance:

• The area where used should be dry and at a comfortable temperature (about 15 - 20 degrees Celsius)
  
  
• The mixing ratio for the standard packs is always 1 part of hardner to 5 parts of resin and must always be measured as exactly as possible (For example 2 ml of hardner to 10 ml of resin or 3 ml of hardner to 15 ml of resin etc.). I find that the standard measuring and mixing containers as supplied are designed for larger quantities than required for the average boat repair/maintenance project. The way round this is to purchase several 60 ml disposable plastic syringes which make measuring out the quantities dead easy. The syringes can also be used many times providing that the syringe used for resin is never used for hardner and the syringe used for hardner is never used for resin. If you do not follow this rule then the stock containers will become contaminated and the shelf life of the resins shortened.
  
  
• It's very important not to mix too much at a time. The curing process generates a lot of heat and if this is allowed to build up the mixture can give off poisonous fumes and either melt or set fire to the container (This happened to me once!!). If it is essential to mix a large quantity then use a metal baking tin or similar where the liquid can spread out thereby losing the generated heat. As a general rule I never mix more than 30 ml (that's 25 ml of resin to 5 ml of hardner) in a disposable plastic drinking cup. Do not use the thick polystyrene foam drinking cups which are designed to minimise heat loss from hot drinks! Also remember that there is only a limited amount of time available before the curing process makes the mixture unusable. It is far better to repeatedly mix small quantities which are completely used than to mix a large quantity and waste most of it.
  
  
• After mixing the resin and hardner the mixture remains usable for about 10-15 minutes at a room temperature of 25 degrees C. (This is referred to as the pot life). After this period the curing process begins to turn the liquid into a gel and it cannot be used. Note that the curing time of the mixture is also dependent on the temperature of the area where it is being used. At temperatures below 25 degrees the curing time and pot life is extended. I have used Epoxy outdoors but note that the minimum recommended working temperature is 5 degrees C.
  
  
• After 5-7 hours the resin will have cured to a hard plastic and further hardening will continue until full strength is attained after 5-7 days.

Step by step guide for mixing

What follows is designed to help those that have never used Epoxy before. It describes all the materials and equipment required and then gives an easy to follow guide to mixing and using.

Materials & equipment

• 105 Resin
• 205 Hardner
• Two 60 ml plastic disposable syringes
• Plastic drinking cups (NOT polystyrene foam as cups made with this will not let the heat of the curing resin dissipate)
• Some wooden mixing spatulas
• Three 1" or 1/2" paint brushes (for coating applications)
• Acetone (for cleaning brushes)
• Glass jam jar (for Acetone)
• Paper towels (e.g. Kitchen roll)
• Disposable gloves

Measuring out the Resin

Measuring out the resin For this example 25 ml of resin and 5 ml of hardner are mixed. Put on the disposable gloves. Open the container of resin. Take one of the disposable syringes (if used previously make sure that it was the one used with resin!). Make sure the plunger is fully depressed then dip the end of the syringe into the resin container. Pull back on the plunger so that the colourless resin is drawn up into the syringe. Lift the syringe partially out of the container so it is possible to see the graduations on the side of the syringe. Gently depress the plunger expelling the excess resin back into the container until it measures exactly 25 ml. (Click picture for larger view)

Expelling the resin from the syringe into the beaker Next take one of the plastic drinking cups and expel all the contents of the syringe into the cup by fully depressing the plunger. Take a clean paper towel and wipe off all the excess resin from the outside of the syringe - it can be re-used at a later date. (Click picture for larger view)

Measuring out the hardner Next open the container of hardner. Take another disposable syringe (if used previously make sure that it was the one used with hardner!). Make sure the plunger is fully depressed then dip the end of the syringe into the hardner container. Pull back on the plunger so that the yellow hardner is drawn up into the syringe. Lift the syringe partially out of the container so it is possible to see the graduations on the side of the syringe. Gently depress the plunger expelling the excess hardner back into the container until it measures exactly 5 ml. (Click picture for larger view)

Expelling the hardner from the syringe into the beaker Next hold the syringe above the plastic drinking cup containing the resin (don't let the syringe come into contact with the resin), and expel all the contents of the syringe into the cup by fully depressing the plunger. Take a clean paper towel and wipe off all the excess hardner from the outside of the syringe - it can be re-used at a later date. Make sure the screw stoppers are firmly replaced on both the containers of resin and hardner. (Click picture for larger view)

Stirring the resin/hardner mixture

Take one of the wooden spatulas and stir the resin/hardner thoroughly in the plastic drinking cup. The manufacturer recommends strirring continuously for 2-3 minutes. Scrape the corners of the cup and the sides to ensure an even mix.

Using the Resin

You will have about 10-15 minutes of pot life to use the resin before it starts to gel in the first stage of curing.

Compiled January 2002