Forum :
Workshop Talk & Building Tips
Topic :
Epoxy resin 101, again.
Hey all this is a re-write of a tutorial thread I made a few years ago. Just trying to help people out who are making sticks and new to using resin. Anyway...
Epoxy resin is popular for several reasons:
It seals and protects very well.
Its durable
Its pretty.
Can brighten tone and increase volume on dark sounding, quiet or unsealed didges.
It is classified as inert when mixed properly and fully cured.
First you have to get yourself some epoxy resin. Sooo, brands? Well I use two.
Klear Koat from US composites is really great stuff. Uber clear (totally blushless), decent price and you can get in large amounts. Now I will use the home depot brand "Parks Super Glaze" or Envirotex in a pinch (although I do not like the smell of Enviro at all).
Here is what I suggest you should have to start with:
Gloves, scale, mix sticks, mixing cup, resin and a mask with vapor filters.
Now I use a scale to measure my resin, if you have to do it manually try and be as precise as possible. The closer to the recommended 1:1, the better your result. When mixing your resin up, make sure it is not cold. Cold epoxy does not mix well, will get bubbly very quick and may not cure very well if mixed and left to cure in colder temps. Using a "goodwill" microwave for no longer than 5 seconds does the trick nicely, so does a little time in the sun. Also pay attention to the "pot life" of your resin. the warmer it is the faster it will begin to cure. Warm resin left unattended in a cup can get hot very fast and lead to burns and a melted ass cup. Be careful! Use you resin as soon as it is mixed. Pictured is the result from an unattended cup of resin in a hot workshop from years ago. It melted the spoon I was mixing with right off!:
So measure it out, mix very, very well until there aren't any "wisps" of unmixed resin and apply using gloved hands or a disposable brush (or by pouring it into the bell end with one end tapped shut if your doing an interior coating, I use making tape) and leave it to cure for at least 12 hours before working with it again.
Surface prep is really important if you want a nice finish. Sand until smooth up to at least 220 grit and remove all of the dust and crap from the outside of the instrument. You can use an acetone wetted rag for this.
Couple tips I have learned over the years. Latex gloves tear easily and one little uncheck splinter you've got resin all over ya. I like nitrile ones better. Also, I were a mask with vapor filters to protect me from fumes. While the fumes aren't as bad as say, polyester resin, you can still developed an allergy to it after a while. I have. Itchy throat and water eyes suck. Its very common among surfboard makers. Speaking of polyester resin, while the cure time is much less and it does cure a little harder than epoxy resin, the blush is heavy, the color is brownish-purple and the smell almost never goes away. I say "if you can smell it, your breathing it, bro" and I stay away. Not good for interiors at all.
Cleanup. Epoxy resin is cleaned up easily with acetone, even partially cured. However, do not use it to clean resin off of your skin! The acetone give the epoxy a direct route through your skin and can be absorbed into you blood. Not good. Using ordinary vinegar works great!
This is kinda basic and I could go on and on about de-lamination, sanding, chemical bonds ect but maybe in another thread. If anyone has questions or wants to add to this please feel free to do so. Good luck.
-Brad E.
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