epoxy joint

[patterndude at comcast.net]

Let me stress that last sentence.  The 75% isopropyl alchohol is 25% water.  The 90% stuff is 10% water.  YOu need to go to Home Depot and buy 100% alchohol, don't use the stuff you get at Walgreens.  Water will not evaporate and stays in the matrix leading to rubbery epoxy.  A little bit may not be too noticeable but the properties are more severely affected.  
   Obviously this only works on open surfaces like wing glassing where there is a thin epoxy layer and exposure to the air for the alchohol to evaporate into.
--Lance


--
District 6 AVP 
www.aeroslave.com

-------------- Original message -------------- 

Thinning the epoxy on this type of application is okay because the solvent will evaporate prior to cure. Just make sure your alcohol does not have water in it.  The epoxy will obtain full properties.



Gray Fowler
Principal Chemical Engineer
Composites Engineering 


<js.smith at verizon.net> 
Sent by: discussion-request at nsrca.org 
01/18/2005 10:52 AM 
Please respond to discussion 
        
        To:        <discussion at nsrca.org> 
        cc:         
        Subject:        Re: Re: epoxy joint



>> Using a "thinned" epoxy as a coating such as on a wing is different because in the very thin coat, the solvent can evaporate before the epoxy cures.  

Gray,

So would you recommend thinning the epoxy when applying the 3/4 oz finishing cloth?  Or should we <possibly> sacrifice a little weight for a better cure/harder surface?

Scott

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