Sticky epoxy coating

Builder's Forum
1

Does epoxy resin degrade in the container if stored in a cold room? (The temperature may have reached 40 degrees or lower for a few nights inside the work area, but not freezing).

When I fiberglassed the bottom of the hull on my Lighthouse Tender Peapod a couple of weeks ago I mixed the cold resin and hardener to the right ratio and mixed well, and then set the temperature to a minimum of 65 degrees in the shed. The coast has remained just a tad sticky overall, although some areas have hardended well. I am not sure if the cause is using cold resin, or not keeping the room warm enough in the first couple of days after application. One of the batches did generate a lot of heat in the cup and quickly became rock solid as I was completing the application, which makes me think the resin was not damaged.

I am planning on applying a second coat to "fill the weave" on top of this first coat with resin that has not been exposed to cold, and also keep the shed above 70 degrees. Is this a good idea? The fiberglass seems well-adhered to the hull surface and the stickiness is minimal. Will the second coat under the right conditions fix this?

Any other suggestions? Other than using cold epoxy and the room temperature, all the other variables in the application were the same as I have used before, I can't figure out another cause.

This is my first build and working with epoxy. Everything was going well until the cold started around here.

Thank you for any pointers.

2

Rule #1 whenn working with epoxy is: store, mix, and apply at temperatures recommended by the manufacturer.

Your stuff may not have been mixed properly at those temps, and it's possible the resin may have crystallized also, leaving some of the important chemistry in the bottom of your containers. Crystallization's not hard to reverse, you just put your resin into a warm water bath (in the containers it comes in!) then once it's warmed and agitated by rolling the container around a bit the crystals will have dissolved.

Store your resin at 60°F or better, preferably 70°F, 24/7/365. Also do your best to mix and then apply the mixed stuff at about the same temperature.

Bring your project's materials up to those temps too before working with epoxy on them. Rising temps is a resipe for outgassing, lower temps will delay your cure.

You may be able to get your sticky stuff to cure if you raise the temp in your workplace, or it may stay sticky. If that happens, scrape it off, wash the rest off with denatured alcohol, start over.

 

3

Hi Jose, 

if at all possible, keeping things above 70 degrees, both the epoxy and whatever it is you are epoxying (e.g.. the hull) takes a lot of potential problems off the table. 

if you can't consistently ensure the work space will stay warm, bring you epoxy inside (assuming you keep your house reasonably warm) so that it does not get cold.

things can work in colder temperatures....but there is just a lot more that can go wrong....so you have to be that much more careful.

epoxy can be damaged when it gets cold and the manufacturers help desk is where i would go for support and they are often a great resource to help you sort out what to do next.  

i have had, many years ago, a problem that sounds pretty much like what you described...where the epoxy never fully cured and remained tacky.   you never know exactly what happened...but we think it was becuase it got too cold...and the MAS technical support recomended i replace my resin which is what i did.

on the problem with your soft epoxy, you can try heating everything up and see if you can get the last bit to cure, but if it doesn't, new epoxy over it will not fix the problem...there will always be a weakness there.   the question then becomes, is the weakness such that you should pull off the un-fully-cured sections and redo it now or just accept it and deal with any other problems down the road.

in my case i went forward and used my boat.   the sections that were not really cured, after a couple seasons, became a problem and i eventually had to remove them and re-glass the boat.  it was interesting to see the fully cured epoxy on top of the gum like uncured stuff.  After about two season,  what happened is blisters started to develop as the glass was never fully bonded to the hull and it eventually gave way.   

refinishing once that happened was not that terrible dfficult so i can't honestly tell you, in hindsight, that i should have stopped and fixed it before moving forward.  when i had the problem the spring season  was just ending and i wanted to get on the water....and i did....and the refinishing project was done on the off season when it did not matter.

anyway, i hope that helps.  but i would check with the manufacturer and also call the clc help number and see what advice they have too.

h

 

 

 

   

4

I agree with above always fix a problem asap.

I built a boat last winter in cold climate and came up with this little simple trick to keep the epoxy warm prior to use. I found a box liner of aluminum coated bubble wrap (from a box that shipped food) cut a hole in the top and fixed it to a desk adjustable engr. style lamp with a incandescent bulb 60w. I keep the epoxy containers in the tent turn on the light several hours or the night before use, raise the arn to expose the pumps when needed and lower after use. It always kept the exoxy warm 70+ great for mixing. Hope this helps. Good luck, Ernie

 

 

 

 

 

 

 

 

 

 

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5

   Thank you eveyone for taking the time to answer. This is very helpful.