[NSRCA-discussion] epoxy question

Tue Nov 27 08:45:00 AKST 2007

West System has quite the web site if you want to know about their  products.

Bruce  Reins
A Stock Hydro/Runabout
15-R  

In a message dated 11/26/2007 9:51:25 P.M. Mountain Standard Time,  
Tom.Koenig at actewagl.com.au writes:

Gents and  Linda

For laying up work,  that is fuselages, cowls etc I use LC3600 Resin. I post 
cure at 80 Degrees C  for 4 hours. I quite like this resin.

For wings I sand like  crazy ( both sides) and seal with dope. Honeycombed 
cores. Then I use  West 105/207 for skins. Never tried to post cure the wings, I 
figured this  epoxy would not benefit from it ( i.e I had no data for it..so 
I  didn't!)

Tom

____________________________________
 From: nsrca-discussion-bounces at lists.nsrca.org  
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Lance  Van Nostrand
Sent: Tuesday, 27 November 2007 2:48 PM
To:  NSRCA Mailing List
Subject: Re: [NSRCA-discussion] epoxy question-I  am back

I use the West system all the time but we use custom blends made up by  
master Fowler for AeroSlave parts after all our R&D on the process  design.  West 
205 hardener gives about 925 cps and the 207 gives about  750.  The thin stuff 
Gray is talking about is half that!
--lance

----- Original Message ----- 
From:  _Pattrnflyr at aol.com_ (mailto:Pattrnflyr at aol.com)  
To: _nsrca-discussion at lists.nsrca.org_ 
(mailto:nsrca-discussion at lists.nsrca.org)   
Sent: Monday, November 26, 2007 11:20  AM
Subject: Re: [NSRCA-discussion] epoxy  question-I am back

I have built several wood racing boats with West System.  The  105/205 is for 
gluing and the 105/207 is for glassing and is much thinner  and easier to 
work with.  I glue the boat together with 105/205 and  then roll on 105/207 for 
the final finish and you are done.

Bruce  Reins
A Stock Hydro/Runabout
15-R  

In a message dated 11/26/2007 8:46:44 A.M. Mountain Standard Time,  
lightfoot at sc.rr.com writes:

West’s 105/205  system seems to be a low viscosity epoxy. It is a slow cure 
(8 hrs) so if  you add solvent it should have plenty of time to evaporate. I 
have only  used it for sheeting, not glassing – yet. 

Jay  Marshall 
-----Original  Message-----
From:  nsrca-discussion-bounces at lists.nsrca.org  
[mailto:nsrca-discussion-bounces at lists.nsrca.org]  On Behalf Of Gray E  Fowler
Sent: Monday,  November 26, 2007 10:23 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] epoxy  question-I am back 

1.  "Thinning the epoxy  saves no weight by evaporation.  There is virtually 
no evaporation  and no weight loss-a big time erroneous assumption on my part. 
 So if  you mix 2 ounces of epoxy and add 2 ounces of thinner and put it all 
on  the airplane, you have added 4 ounces to the airplane.  " 

After seeing the real question  I expected a weight increase of at least 9% 
(how much water in the mix).  If you put 1oz (by weight) of solvent in 1 oz of 
epoxy, and apply it as a  coating , thin, you will eventually end up with 1 oz 
of epoxy. Mike, your  solvent got trapped, and now it will have less 
adhesion, less tensile,  Compression and flexure strength, and will now shrink slowly 
as the  alcohol exits the cured epoxy, over a year or so (see Wayne's  
answer). 

None of the solvent's listed  will react with any epoxy blend. Exotherm is 
negligible when applied as a  thin coating, but significant in mass. The ability 
to have the solvent  evaporate out of the epoxy coating is directly related 
to the mixed  viscosity of the neat epoxy blend and the cure rate of the epoxy. 
Those of  you who ran experiments with 5 minute epoxy reported bad results 
because  of high viscosity and fast cure rate.The high viscosity (even Mike's 
blend  is apparently too high) will cause a skin effect where the solvent  
evaporates from the surface first, creating a high viscosity skin, then  the epoxy 
starts to cure increasing viscosity even more, thus trapping the  solvent. 
Using fiberglass makes this even worse. MIKE- in one year from  now your wings 
will weigh less. 

So it sounds like  the the Pattern Dudes of the world need a solution.  What 
AeroSlave  can do is provide a super low viscosity epoxy for sale. This will 
be 100%  solids (which means NO solvents). Chances are, as a mixed epoxy, the  
viscosity will be lower than even blends with some solvent in them. This  can 
be used to apply fiberglass to wings or as a general laminating  resin. 

How much interest would there  be for such a a product? It would probably 
cost about $50/ quart, $25/  pint. It would absolutely require an accurate scale 
(+/- 1 gram) to WEIGH  the epoxy and hardener into the appropriate mix ratio. 
AND I offer no  warranty, simply because you guys are the biggest bunch of 
experimenters  in the world, and I cannot control, nor anticipate how this could 
get  screwed up. 

1. Operator cannot operate a  scale. 
2. Operator has a crappy  scale. 
3. Operator added solvent  anyway because thats how he has always done 
it...since 1976  
4. Operators basement is 100%  realative humidity..condensation on the wing. 
5.  Operator added "more" hardener to make it cure faster.  
6. Operator......(enter F/U  here). 

As you can see there is one  common theme to all of these possible problems, 
Operator, i.e.  customer. 

So if you are STILL interested  please respond and Lance and I will take it 
under  advisement. 

Gray  Fowler
Senior Principal Chemical Engineer
Radomes and Specialty  Apertures
Technical Staff Composites  Engineering
Raytheon 

"Dr.  Mike Harrison"  <drmikedds at sbcglobal.net>  
Sent by:  nsrca-discussion-bounces at lists.nsrca.org  
11/23/2007 01:57  PM      
Please  respond to
NSRCA Mailing List  <nsrca-discussion at lists.nsrca.org> 

To  
"NSRCA  Mailing List"  <nsrca-discussion at lists.nsrca.org>     
cc  

Subject  
[NSRCA-discussion]  epoxy question 

I have  read with interest all the comments and some of you have educated me 
on  this issue.  If I may, I will share what I have  learned. 

1.  Thinning the epoxy  saves no weight by evaporation.  There is virtually 
no evaporation  and no weight loss-a big time erroneous assumption on my part.  
So if  you mix 2 ounces of epoxy and add 2 ounces of thinner and put it all 
on  the airplane, you have added 4 ounces to the airplane.  
2.  The properties of the  epoxy are changed-it becomes rubbery. 
3.  Changing  the properties is not an issue regarding finishing the  
airplane(painting) 
4.  Using thinned epoxy  is fine for applying glass cloth. 
5.  I have  tried MEK(epoxy thinner), denatured alcohol, 91%alcohol, acetone. 
 My  preference is denatured alcohol because it is the safest and most  
economical, I think.  I thought MEK would be the answer.  It is  the worst of the 
bunch.   
6.  The best  way to glass surfaces is to thin the epoxy and apply as 
sparingly as  possible.  A way to do that is to apply and wipe off excess with  paper 
towels.   
7.  It is almost exactly  2 ounces to glass a wing panel complete, so 4 
ounces for a whole wing.  About 2 ounces for a stab.  Properly done wings and stab  
glassed and painted is 2-2.5 times the weight of monokote.  
8.  A second thinned coat  of epoxy on the glassed wing is .75 ounces each 
wing panel-1.5 oz  total. 

Pick your  poison. 

Later, 
Mike  
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion  

_______________________________________________
NSRCA-discussion  mailing  list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

____________________________________
 Check out AOL Money & Finance's list of the _hottest products_ 
(http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)  and _top money 
wasters_ 
(http://money.aol.com/top5/general/ways-you-are-wasting-money?NCID=aoltop00030000000002)  of 2007.

____________________________________
_______________________________________________
NSRCA-discussion  mailing  list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

_______________________________________________
NSRCA-discussion  mailing  list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

**************************************Check out AOL's list of 2007's hottest 
products.
(http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20071127/99c8095f/attachment-0001.html 