Nate-RCU

Hi all,

Just wanted to know the best way to "thin" epoxy for fuel proofing the firewall and side pieces. The ARF I have now has this area painted but the ply does not look to be sealed. Also does it matter what paint you use to top coat it with??

Thanks ,

Regards,

Nate

vkernus

My Feedback: (1)

The best way I have found to thin epoxy is to mix in some denatured alcohol. Works great and acts as a good fuel proofer. As for top coat, yes it does matter which paint you use. If you don't use a fuel proof paint such as dope, rustoleum or the like, the glow fuel can ruin it.

Victor

Nate-RCU

Thanks vkernus!

Are you saying that the denatured alcohol can be a substitute for fuel proofing by itself?
That would certainly make it less messy and cheaper

Regards,

Nate

dr_wogz

My Feedback: (3)

A few drops are all you need.

Others will chime in, with teh 'don't do it' as teh alcohol does weaken teh epoxy.. But it's fine for fuel proofing.

Alternatively, you can heatrt eh epoxy, nuke it a bit, or use a 'double boiler (a mug of hot water) when mixing teh epoxy, but it curews much faster! use 30 minute or longer if heating it.

J_R

Use at least 30 min epoxy. Denatured alcohol works well to thin it. I use a 1:1:1 mix.

If you use a faster setting epoxy, it may trap the alcohol before the alcohol has time to evaporate.

Most any paint over epoxy is compatible. As vkernus said, it must be fuel proof/resistant, or the paint will be attacked by fuel. The epoxy will be inert to fuel.

Also, consider that aliphatic resin (yellow wood glue) is fuel proof when cured. It can be reduced with water. It is my choice for fuel proofing the interior of the aircraft.

Edit: do not use rubbing alcohol, it has water in it and does not evaporate fast enough and can make the epoxy rubbery.

vkernus

My Feedback: (1)

Nate,

No, denatured alcohol is not a substitute. The denatured alcohol must be mixed in with the epoxy. The denatured alcohol will thin the epoxy to a consistency that will allow you to apply it easily with a brush.

You do not need to add much. Also, while there are those that say it will weaken the bonding quality of the epoxy (probably true to a degree) as fuel proofing, you are not looking for bonding properties.

Victor

vkernus

My Feedback: (1)

JR,

Aliphatic resin is fuel proof when cured? That is good to know!

Thanks,

Victor

Nate-RCU

Thats great!

Thanks for the answers. I think I will try the Epoxy and denatured alcohol way as described. I didn't know that carpenters glue would also work.

Regards,

Nate

J_R

vkernus

Yes, it is fuel proof. Be aware that it is available as interior or exterior use. It is not water proof and does not stick well to covering, so is not a good choice for firewalls.