B

bmurrish

Well Known Member
Does anybody know the proper mixture for the West Systems #105 resin and West Systems #205 hardener? I was attempting to finish my fiberglass empennage tips with the stuff and it didn't work. I carefully measured and mixed it according to the directions on the cans of 5 parts resin to 1 part hardener. I quickly laid down 3 layers of 4oz S-glass worrying that I wouldn't have enough time between layers. Well, 4 hours later, the stuff still has not cooked off. It is runny and just feels tacky. The temp in my basement is around 72 degrees and pretty much no humidity. I can't figure out what happened. Are the directions on the cans wrong?
 
Bill:

That is the right ratio. Try placing a shop worklight close to your part you laid up to warm it up a bit. Should kick it off.


Regards,
 
Bill,
There might be a bit of blending time required on that epoxy, I do not have the spec sheet for it so I do not know for sure. However, even epoxy primer requires about 40 minutes of blending time after mixing. This time is required for the different molecules to all shake hands and get to know each other. After they do that they get excited (warm) and the layup will harden properly. Always get a spec sheet for any new materials that you buy. It may be available on the web.
Cheers, Pete
 
Blending the epoxy and hardener is the secret!

I use the West System with the pumps on each can. One big pump of the resin and one little pump of the hardener go into a small paper cup to give the perfect 5-to-1 ratio. I use a popsicle stick to blend the two clear mixtures together for about 30 seconds mixing vigorously. If you watch the mixture in the cup under a bright light, you will see it get slightly translucent (milky) as the two clear mixtures blend. Like the man said, it also gets a just a bit warmer as the interaction takes place. With the slow hardener, you will get about 30 to 45 minutes of working time (depending on ambient room temperature) before the stuff becomes unworkable (kicks as some say). It will be tacky for several hours. I always leave my work until the middle of the next day before I try to do anything else with it.

Jerry K. Thorne
East Ridge, TN
RV-9A N2PZ
 
west system mixing

I have been using west system for over 15 years and very happy with it.
ratio isn't an exact science as I at times depress the pumps each a 1/3 by
guess or maybe a 1/2 depending on the amount that I'm using. At 70* I never try to do anything before 24 hours and can usually start sanding with
50 grit to remove high spots then work to finer grit unless I need more layup.
Paper will gum up so wet or dry with water is much better as the paper will stay clean.
Ted
 
West system mixing

I forgot to add that westsystem epoxy takes 5 to 7 days to totally cure depending on tempature.
Ted
 
Guys... WEST epoxy details are here....

http://www.westsystem.com/frames/tier2/usingepoxy/usermanual.htm

Jerry is a bit quick with his 30 seconds of mixing...:^)
WEST says 1 minute minimum, and take care to scrape the sides...
Unlike some epoxy primers there is no blending time (induction time) needed after mixing.

Follow the manufacturer's instructions for the best results....

gil in Tucson EAA Technical Counselor

If it's your first time using any product, do a test sample first... don't test on your project if at all possible....
 
Thanks for the tips everyone. Before I mixed it I did download the data sheat from West System. I did use the wax free dixie cup measuring method and mixed it for the specified one minute with a wood stick. I got a little worried after the stuff had not "went off" in over 6 hours so I pulled it off and threw it in the garbage. I was affraid my mixture wasn't right and didn't want a weak final product. This morning I checked the stuff in the garbage and it was hard. I guess I was a little concerned because I was expecting only a 7 minute pot life. Live and learn. I will try it again, this time expecting a longer cure time. Thanks again.

Note to self: Thank God I am building a RV and not a glass airplane.
 
Bill,

Glad it worked out. I was surprised at how long the epoxy takes to set up compared to polyester resin. I would strongly recommend the West System pumps. They are SUPER convenient.

Steve Zicree
 
You must log in or register to reply here.