2409Hrs – Groundhog Days
The weather is the same, the work is the same but change is coming for both. Another two planks glued today and now only two remaining, I’ll get them finished tomorrow. My fresh epoxy supplies arrived today and is stored away safe in the epoxy shack nice and warm.
On the subject of temperature and epoxy thanks to Mike for his question regarding the necessary working conditions for epoxy. First off I should clearly state that I’m not an expert, I’ve become very used to working with the Sicomin products I’m using to build ‘Gleda’ but I have no real knowledge or experience with other brands.
I’m using Sicomin SR5550 resin and two different hardeners, a fast and a slow, epoxy cures by a combination of exothermic heat generated by the chemical reaction of mixing resin and hardener together and ambient temperature. In my build barn I can’t control the ambient temperature but I can control the epoxy to some extent. Firstly I keep the resin and hardener in a wooden box heated with a light bulb, this maintains a nice even temperature which allows the resin and hardener to flow and mix easily. Cold epoxy becomes treacle like making thorough mixing virtually impossible. Secondly I use a hardener to match the ambient temperatures so at the moment I’m using fast, to be honest I’ve never used slow on it’s own, in the UK summer I mix 50/50 fast and slow to get a ‘medium’ that works well for me.
Using the above methods I have found that even in temperatures close to or just below freezing the epoxy will cure to give a strong bond after 12-18 hours but until the temperature rises close to double figures (‘C) it won’t lose it’s tack nor will it reach it’s full strength.
This is fine for the work I’m doing at the moment because it’ll be well into Spring by the time these beams get any stress but if I’d needed immediate full structural strength or to sand back next day I’d have had to wait for things to warm up.
I’m pretty sure that Jacques Pierret also queried his epoxy supplier (MAS) about this subject when he was building his beams in a New Jersey winter and was told it was no problem.