Permatex Versus Polysulfide

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Doug2233

Well-Known Member
Joined
Jan 10, 2011
Messages
48
Location
Sydney, Australia
Unless the Permatex is a poly-sulphide I wouldn't trust it.

Poly-sulphide is a miracle product in terms of its resistance to hydrocarbons and to water. Very few products achieve this, plus the poly-sulphide remains flexible so does not become brittle and crack.
 

GESchwarz

Well-Known Member
Joined
Oct 23, 2007
Messages
1,179
Location
Ventura County, California, USofA.
One thing I understand is that Permatex is only designed as a sealant between close-fit mating surfaces, such as gasket surfaces, and threaded joints.

I have just initiated a test to see what gasoline does to a piece of old Permatex.

I have just concluded a test to see how aerospace epoxies withstand gasoline. They don't do well. In time they lose their grip on aluminum, turn to a lighter shade of grey, and becomes weak and brittle.

So my next question is, could a flexible fuel bladder be made of a composite of fiberglass and Polysulphide?
 

TinBender

Well-Known Member
Joined
Mar 4, 2010
Messages
218
Location
Charlotte, NC, USA
There are epoxies that are specifically formulated for resistance to gasoline. For example Jeffco 9700:

RHINO FUEL TANK SEALER 9700 A/B FRC from Aircraft Spruce

Thanks, Bob K.
Does not look incredibly compatible with ethanol, though.

From Rhino literature:


CHEMICAL RESISTANCE GUIDE (3 week immersion)
Reagent ......................% weight gain (loss)
Ethyl Alcohol ................6.9
Mogas, Diesel ...............0.0
JP-4, JP-5, JP-7, JP-8 .....0.0
 
Last edited:

Rockiedog2

Well-Known Member
Joined
Dec 11, 2012
Messages
2,318
Group Builder
Top