Desmoducky
Husqvarna
AA Class
I started to disassemble the 1972 CR 450 I bought through Craigslist. The inside of the gas tank was full of rust. I removed almost 1/2 quart of rust flakes. Needless to say, the tank is extremely pitted inside and is most likely quite fragile in certain areas. So I need to line the tank and I'll probably choose a two part phenolic novalac epoxy system like Caswell's system.
Now, I've heard horror stories of these systems failing but let me tell you what... the manufacturer's directions that most people follow (to the letter) are not good enough. So let me tell you how to do it correctly. I have a heck-of-a-lot of experience with epoxies. So you know have the opportunity to learn from my mistakes without paying out good money for a bad job.
First-off, we all know that we need to get as much of the rust out as possible. Whether you use electrolysis, apple cider vinegar, Metal Rescue or CLR, get that crap out! Put sharp edged gravel inside and rock-n-roll that bad-boy until all the loose stuff comes off the side walls of the tank. Follow that by washing the tank out again with clean rust remover... let it set and work it's magic. Then wash it out THREE times with clean acetone.... not once, not twice... but three times. You'll hate yourself if it doesn't turn out perfectly, so darn it, do it right!
Mask you tank off completely. The whole tank... if you think you're good enough to not get epoxy everywhere, let me tell you, you're not because I'm not! So wrap everything you wouldn't want contaminated on the outside. Want to do it half-assed? Please see directly below:
THAT'S NOT GOOD ENOUGH!
Now, when you mix the epoxy in the plastic container, follow the mix ratio, don't go getting all experimental on me. Eye-balling it isn't good enough. Get the measuring cup that's required to get the proper mix ratio. Don't be tempted to add more catalyst than what is called for. The epoxy "Hit" reaction is exothermic and can be weakened due to the buildup of heat.
The manufacturer's instructions tells you to mix the epoxy real good in a container so you don't get any unmixed epoxy going into your gas tank, thus ruining the liner.
THAT'S NOT GOOD ENOUGH!
After you mix the epoxy in your plastic container, transfer it to a a SECOND clean plastic container and mix it again. The first container will still have a slip film of unmixed epoxy along the inside walls of the container. I don't care how good you think you are at getting rid of that slip film, you aren't, because I'm not!
THIS IS WHAT SCREWS UP EVERYTHING! DO YOU HEAR ME, GOMER PILE?
By transferring your mixed epoxy to the second container, the slip film is entirely eliminated. Other wise, you could end up with what we call "hot spots" which are streaks of unmixed-uncured base resin along the inside of your precious Husqvarna tank. It will remain sticky and will eventually be dissolved by your gas/oil and allow moisture to get behind the liner coating and compromise the entire job. You will hate yourself for not doing exactly as I say.
DOUBLE MIX YOUR EPOXY...ALWAYS...WITHOUT EXCEPTION! DON'T MAKE ME TELL YOU AGAIN! HAVE I MADE MYSELF PERFECTLY CLEAR?
If in the event, you do not do as I say, please feel free to PM me with your telephone number so I can call you up and rag you out for not following my explicit instructions.
The next step I take, I realize that not everyone can do. But I'm in the business, so I have the equipment. Whenever you mix epoxy (and mix it twice... YOU MADE ME SAY IT AGAIN!), you are air-entraining the mix. Millions of tiny air bubbles are being added to the epoxy every time you whip your stirring stick around the mixing containers (read plural!). So to remove the air bubbles, I put the freshly mixed resin in my vacuum chamber and suck the air out of the mix. It takes less than a couple of minutes but this method makes the epoxy mix smooth, glass-like and absolutely bubble free. By eliminating the air, the liner is also as strong as it can possibly be. all possibilty of bubble trails are eliminated (linear trails of connecting bubbles). In addition, when the epoxy is pour it into your tank, none of the bubbles will cling to the side of the tank and form an air space which allows a pin-point of oxygen for possible rust to develop.
Now, rotate that tank over and over until you are completely sure you have coated every square inch (or square centimeter for you across-the-pond lads) of surface. Are you sure. Good!
NOW, DO IT AGAIN!
Make sure you didn't clog the Husqvarna gas tank connecting tubes underneath the tank. Fill those bad boys with play dough or something similar so you can remove it later with a stiff pipe cleaner. Drain the tank of the excess epoxy back into your mixing container and let that bad-boy cure out. Check the connecting tubes every once in a while to make sure they are open.
When completely cured, the tank lining will be as close to perfect as you can make it.
I hope you had fun. If so, then say; "Yes, Drill Sargent!"
Lucien
Now, I've heard horror stories of these systems failing but let me tell you what... the manufacturer's directions that most people follow (to the letter) are not good enough. So let me tell you how to do it correctly. I have a heck-of-a-lot of experience with epoxies. So you know have the opportunity to learn from my mistakes without paying out good money for a bad job.
First-off, we all know that we need to get as much of the rust out as possible. Whether you use electrolysis, apple cider vinegar, Metal Rescue or CLR, get that crap out! Put sharp edged gravel inside and rock-n-roll that bad-boy until all the loose stuff comes off the side walls of the tank. Follow that by washing the tank out again with clean rust remover... let it set and work it's magic. Then wash it out THREE times with clean acetone.... not once, not twice... but three times. You'll hate yourself if it doesn't turn out perfectly, so darn it, do it right!
Mask you tank off completely. The whole tank... if you think you're good enough to not get epoxy everywhere, let me tell you, you're not because I'm not! So wrap everything you wouldn't want contaminated on the outside. Want to do it half-assed? Please see directly below:
THAT'S NOT GOOD ENOUGH!
Now, when you mix the epoxy in the plastic container, follow the mix ratio, don't go getting all experimental on me. Eye-balling it isn't good enough. Get the measuring cup that's required to get the proper mix ratio. Don't be tempted to add more catalyst than what is called for. The epoxy "Hit" reaction is exothermic and can be weakened due to the buildup of heat.
The manufacturer's instructions tells you to mix the epoxy real good in a container so you don't get any unmixed epoxy going into your gas tank, thus ruining the liner.
THAT'S NOT GOOD ENOUGH!
After you mix the epoxy in your plastic container, transfer it to a a SECOND clean plastic container and mix it again. The first container will still have a slip film of unmixed epoxy along the inside walls of the container. I don't care how good you think you are at getting rid of that slip film, you aren't, because I'm not!
THIS IS WHAT SCREWS UP EVERYTHING! DO YOU HEAR ME, GOMER PILE?
By transferring your mixed epoxy to the second container, the slip film is entirely eliminated. Other wise, you could end up with what we call "hot spots" which are streaks of unmixed-uncured base resin along the inside of your precious Husqvarna tank. It will remain sticky and will eventually be dissolved by your gas/oil and allow moisture to get behind the liner coating and compromise the entire job. You will hate yourself for not doing exactly as I say.
DOUBLE MIX YOUR EPOXY...ALWAYS...WITHOUT EXCEPTION! DON'T MAKE ME TELL YOU AGAIN! HAVE I MADE MYSELF PERFECTLY CLEAR?
If in the event, you do not do as I say, please feel free to PM me with your telephone number so I can call you up and rag you out for not following my explicit instructions.
The next step I take, I realize that not everyone can do. But I'm in the business, so I have the equipment. Whenever you mix epoxy (and mix it twice... YOU MADE ME SAY IT AGAIN!), you are air-entraining the mix. Millions of tiny air bubbles are being added to the epoxy every time you whip your stirring stick around the mixing containers (read plural!). So to remove the air bubbles, I put the freshly mixed resin in my vacuum chamber and suck the air out of the mix. It takes less than a couple of minutes but this method makes the epoxy mix smooth, glass-like and absolutely bubble free. By eliminating the air, the liner is also as strong as it can possibly be. all possibilty of bubble trails are eliminated (linear trails of connecting bubbles). In addition, when the epoxy is pour it into your tank, none of the bubbles will cling to the side of the tank and form an air space which allows a pin-point of oxygen for possible rust to develop.
Now, rotate that tank over and over until you are completely sure you have coated every square inch (or square centimeter for you across-the-pond lads) of surface. Are you sure. Good!
NOW, DO IT AGAIN!
Make sure you didn't clog the Husqvarna gas tank connecting tubes underneath the tank. Fill those bad boys with play dough or something similar so you can remove it later with a stiff pipe cleaner. Drain the tank of the excess epoxy back into your mixing container and let that bad-boy cure out. Check the connecting tubes every once in a while to make sure they are open.
When completely cured, the tank lining will be as close to perfect as you can make it.
I hope you had fun. If so, then say; "Yes, Drill Sargent!"
Lucien
