Talk Composites - The Forum for Advanced Composites

Noob Questions: Coating Vs Laminating Vs Gelcoat

http://www.talkcomposites.com/Topic12828.aspx

By Kalix - 9/10/2014 12:30:43 PM

Hi Guys,

There's plenty of info online about coating and laminating resins, but I still can't figure out the difference.
I'm sure 5 minutes with the correct person would answer all my questions, but I haven't been able to find that person in my area! Smile

I did use the search to find similar topics before posting, but couldn't find my answer (apologies if this exists on the forum elsewhere).


To a layman (that's me!), laminating and coating seem like synonyms, what is their specific conotation in the world of composites and resins?
What is the difference between EL2 Epoxy Laminating resin, Epoxy Coating resin and Epoxy Gelcoat ? (the ones on easycomposites sales page for example)


Finally, I have a carbon-kevlar canoe polo boat that has been badly UV damaged, and the resin has flaked off.
Recoating this, what should I be using? Laminating resin? Coating resin? or Gelcoat? Maybe even just regular repair resin would work?



Thanks very much for any help, hopefully I can pass any knowledge forward in the future (kayaking is getting more popular around here!)
By Hanaldo - 10/5/2014 12:40:18 PM

Yes and no. Depends on the application, the process used etc. Gelcoats are generally sprayed or brushed on, and largely perform the same function as paint. Generally you would apply a gelcoat to the surface of a mould, or in the case of tooling gelcoat, to the surface of a plug. They are thixotropic (not the same as thick, a substance can be thick without being thixotropic) and don't need to self level, because they take on the surface of the mould or plug. Coatings on the other hand are generally applied to an already completed laminate. To reduce the amount of finishing work, they need to have good self-leveling properties. Often the function of gelcoats vs coatings cross over, and which one you use is dependant on the application and the process you are using. 

In regards to the difference between laminating and coating, you are talking about the products on a broad basis. A laminate is any material that is built in layers for the sake of improving or adding desirable qualities to the final laminate. So laminating a book for example, is the process of adding a layer of plastic to a 'layer' (the book) of paper. Plywood is a type of laminate, car windows are a type of laminate. It's just the processes used that differentiate them. Fibreglass and carbon fibre are laminates, layers of fibres held together by a matrix of resin. Hence, the resin used for this is called laminating resin.