PDA

View Full Version : Epoxy Removal



Tim Clarke
03-13-2005, 07:34 PM
I have here a aluminum casting that needs to have a crack welded. Problem is, some yokel has slobbered what appears to be JB weld all over it. Some will come off easy, with the grinder. Some more will be removed when I vee out the crack. However, the backside will be a bugger, there isn't much room to work. If I warm the thing up, can I peel the stuff off, like bondo?

any thoughts appreciated, thanks Tim

IOWOLF
03-13-2005, 07:48 PM
warm it and cool quickly.

aboard_epsilon
03-13-2005, 07:49 PM
hmmm
I know that Acetone is the solvent for polyester resin (grp)
and i think...methyl ethyl ketone is the solvent for epoxy....if you can get the stuff .....
not sure about the dangers involved.
and it would probably have to be soaked for hours.
all the best.mark

Tinker2
03-13-2005, 07:50 PM
300 degrees will soften it but it will still be a mess to remove.
It will make it like it is before it sets up. Good luck.

Be Safe http://bbs.homeshopmachinist.net//smile.gif

CCWKen
03-13-2005, 08:05 PM
Soak in hot antifreeze overnight and it will crumble away like dried bread. Don't ask how I know this. http://bbs.homeshopmachinist.net//frown.gif

ALSO: Don't use JB Weld to repair a radiator!

Jpfalt
03-13-2005, 08:10 PM
If it truly is epoxy there isn't much you can do. The MEK solvent only works when the epoxy is uncured, but won't touch it once cured. The material will char before it melts. You will probably just want to leave it in place and do the weld in a ventilated area.

If the material is a resin like polyester or styrene, then acetone, carb cleaner or acetone will dissolve it, but that is unlikely if the casting is part of an engine and has been in contact with gasoline. It will also melt and flow when heated.

darryl
03-13-2005, 11:11 PM
Overheating epoxy can sure stink up a room for days. That's one of the things I try really hard to avoid. I think it's carcinogenic as well. It certainly is something to do outside.

shawnspeed
03-14-2005, 10:23 AM
Almost all epoxy will lose it's bond at 400 degrees F. I have regularly removed the stuff from aluminum castings this way,and it works as well as anything else,but it does stink. Outside with a O/A torch is my preferred method. DO NOT use your wife oven, it will get you in the doghouse but quick! Good luck ,Shawn.

thistle
03-14-2005, 04:06 PM
epoxy really does not like heat,so try a hot air gun on it ,or pop it in the ovenand scrape it off.
in the course of fixing boats and boatbuilding have slathered lots of fasteners fittings ect with epoxy to keep whatever put, to release say a screwor bolt you can just touch it wih a bit of heat and
the epoxy lets go,hit the thing with a wire brush to remove the damaged epoxy.

debequem
03-14-2005, 05:04 PM
http://www.hisglassworks.com/pages/attack.html

sauer38h
03-14-2005, 11:54 PM
Run-of-the-mill epoxy doesn't have to be really hot to decompose. I've had good results immersing parts with errant epoxy in boiling water. The epoxy doesn't dissolve, but it loses its strength and gets gummy. It has to be scraped off, but it doesn't have to be chipped or ground off.

There are high-temprature epoxies which won't decompose at such a low temperature.

I've never tried this with JB weld and can't say how it will work, but it's often easy to try.

jfsmith
03-15-2005, 12:44 AM
Lacquer thinner, read the label, it softens epoxy up.

Jerry

ahidley
03-15-2005, 07:45 AM
alcohol makes it fall off.. but it will take a few days. (patch a hole in a gas tank and it will hold till winter when you put in drygas, dont ask how I know!)

Rich Carlstedt
03-15-2005, 05:59 PM
my company bought a machine that i was to rebuild for another purpose.
It was used as a Epoxy Glue applicator, so needless to say it was covered up to 4 inches thick.
I packed it in dry ice,and when really cold ( -50 ?) and hit it with a air needle gun, like the welders use.
The glue cracked off, like stale bread