swift-solo
[Top] [All Lists]

Re: 410 magic brown bog!

To: "rowr" <rowr@xxxxxxxxx>,<swiftsolo@xxxxxxxxxxxx>
Subject: Re: 410 magic brown bog!
From: "Greg Ryan" <gregoryrryan@xxxxxxxxxxx>
Date: Thu, 3 Feb 2005 02:20:57 -0500
References: <000e01c5092f$ff646690$f9c8ba89@yourxwfh6g334c> <BAY102-DAV154E2C3F9830470A6FD0D5CA7E0@phx.gbl> <002f01c509a5$979cb2d0$f9c8ba89@yourxwfh6g334c>
410 is really a great product. There is nothing like it for sculpting a part 
from solid epoxy.However, it has severe limitations in some applications.   410 
feels like its a plastic and decreases the strength of a fillet or joint 
markedly. It seems to melt or become plastic  at especially low temperatures. I 
use 410 "A LOT" because I really don't like sanding hard epoxy. I have cans and 
cans of it. 

 If you intend on using 410 to fair the bottom of the boat remember to fill the 
weave with hard epoxy first so that the texture (or its reverse) of the glass 
weave does not "print through" the 410. Print through is something I have 
observed with gelcoat (on my 49er) and much more so with thin coats of 410 in 
epoxy that I have put over repairs. 

Moreover when you are making parts that need building up or sculpting if you 
increase the amount of 410 to make a thick peanut butter you might notice that 
the surface never really gets hard. I have tried all sorts of ways to get it to 
set up harder on the surface including autoclaving, boiling, baking and peelply 
none worked well.  To  get around this  I usually include some flumed silica 
with somewhat less % 410 when I want a more thixotropic (non-sagging, stiff) 
mix that will get hard on the surface. Of course its harder to sand and 
probably not much stronger. 

Finally if you do use a high % 410 you will get a nice surface as it is kind of 
self leveling (my favorite labor saving technique) but you might especially 
notice the greasy film (amine blush????) on the surface after the set. Its best 
to sand or otherwise wash this off before secondary bonding.  The surface 
becomes a little tacky after acetone wash, for secondary bonding this may be 
good. 

Greg





----- Original Message ----- 
  From: rowr 
  To: swiftsolo@xxxxxxxxxxxx 
  Sent: Wednesday, February 02, 2005 11:05 PM
  Subject: Re: Epoxy and bolts


  While researching my material on epoxy and temperature, I came across an 
interesting comment. It is not verified in any way and I am not sure if it is 
true, it may even be from an outdated source, but goes something like this:

        From "Construction Notes" Falco Builders Letter, September 1992
       

  Stuart Gane was alarmed to discover a warning that West System 410 Microlight 
filler is sensitive to elevated temperatures and that the material can swell 
when hot. Stuart writes, "I have been informed by Brian Knight of Gougeon Bros 
that the filler is probably going to be OK in the temperate climate of the UK, 
if I were to paint my Falco red. However, he did warn me that if I were to fly 
my aircraft to, say, the Mediterranean or wherever the air temperature exceeded 
the 70-80°F range, I could expect the sanding marks left by the rubbing-down 
process to show through the paint or, even worse-where there is a substantial 
thickness of Microlight filler-a swelling of the filler could occur, because 
the filler is a thermoplastic material. Only light colors would overcome this 
problem." Glass and phenolic microballoons are not affected in this way.

  Is there anything in the class rules that prohibits using vast quantities of 
410 and then sailing in the heat to achieve more bouyancy when it swells 
up..... LOL. I think that my sailing style is going to be really beneficial 
here, because I get my deck completely wet every five minutes or so. 

    ----- Original Message ----- 
    From: Greg Ryan 
    To: rowr ; swiftsolo@xxxxxxxxxxxx 
    Sent: Wednesday, February 02, 2005 10:04 AM
    Subject: Re: Epoxy and bolts


    Fabulous practical observation Roger, Thanks.
    But, do you really mean Celsius not Fahrenheit? 120-130F is only 48.8-54.4C
    Im guessing the bolt might need to be quite a bit hotter than that. Im 
fairly confident that my black 49er mast has been much hotter than that over a 
long period and many cycles and its stiffness (which is obviously functionally 
measurable) has not changed all that much. So Swift builders need not bee too 
anxious that your new boat will melt if you spill a cuppa tea on the deck. I 
regularly autoclave my epoxy containing instruments at work so I am interested 
in this phenomenon from another angle.

    The degradation in properties of advanced composites, such as 
graphite/epoxy, by exposure to elevated temperatures is a concern also of  NASA.

     Here is some info I dug up and I'm selectively paraphrasing here -

     Studies have shown that Graphite/epoxy composite materials exposed to 
temperatures in the range of 177 C to 232 C (350 F to 450 F) can affect the 
resin matrix sufficiently to degrade the mechanical properties. 
    In the temperature range below about 177 C (350 F), the dynamic modulus, 
G*, as a function of strain amplitude were seen to be within the viscoelastic 
range. Although there is also some evidence of changes in the range of 50C to 
177C, (chemical changes that im sure cannot be reversible) extreme aging at 
temperature (10,000 hours at 121 C) studies have shown mixed results with some 
graphite/epoxy laminate schedules exhibiting sheer strength decreases of up to 
68% and yet other graphite/epoxy laminates increased in their sheer strength(up 
to 32%). 
    References available if anyone is interested.

    Figure 6. Interlaminar Shear Strength as a Function of Temperature and 
Exposure Time

    Greg


    ----- Original Message ----- 
      From: rowr 
      To: swiftsolo@xxxxxxxxxxxx 
      Sent: Wednesday, February 02, 2005 9:03 AM
      Subject: Epoxy and bolts


       If you inadvertently let some epoxy get into a hole and then forgot to 
take the bolt or screw out, chances are, the bolt is in there for good. Even an 
easy out will battle to remove the bolt. 

      SO, by this stage, you have already stripped the bolt head and cannot 
drill it out because then you will drill into your T-nut which is already in 
your beautifully sealed hull......

      Here is a little tip for getting a bolt out . Epoxy starts getting soft 
at about 120- 130F, so much so that there is a large debate going on in the 
homebuilding aircraft market about using epoxy on wings, then painting the 
aircraft black. Some manufacturers are suggesting that they paint all aircraft 
a light colour if they live in a hot zone of the world. The results of a black 
aircraft sitting in the tropical sun and then taking off with gooey wings could 
be ... interesting.

      Anyway, back to getting the bolt out. Take a very small size DULL drill 
bit and drill into the centre of the bolt. This will heat the bolt up to such 
an extent that the epoxy will soften enough to remove the bolt with a pair of 
pliers.

      happy building
      Roger

GIF image

<Prev in Thread] Current Thread [Next in Thread>

This is the Swift Solo mailing list archive. Visit here to see instructions on how to subscribe and unsubscribe from the list, and to browse the mailing list archives.