Fiberglass Tank Fix (2011)

Thanks,
I've put an email into a company with novolac resins. But like you said they only sell in large quantities, hopefully they might do something for me.
As far as the resin goes, I think they sell a pretty good novolac one.  
To clarify, I should be roughing up the tank surface with crushed glass to provide better adhesion?
And when sealing the tank back together there is no way of getting fiberglass on the inside of the seam, just resin with fiberglass in the out side of the tank? 
Thanks again, I just want to make sure I get the two tank halves sealed back together correctly.

There are a few resin producers here in the UK who produce suitable material. But a good option is to try and find someone producing something like composite fire doors, or parts for the military, which will almost certainly be made using novalac VE resins, and see if they will sell you a small quantity?

I'm learning the best ways and materials from carbon's posts too, but jeeze louise is all that required just to get a tank to hold new fuels and stay intact till crashed?

Glass beading is great but similar etch-bite roughness can be done by hand pick pecking and/or knife/razor slicing cross hatching or even course sand paper. I use a vibra tool or knife point to get a bit of proud material up, unless I had to do a whole tank surface then the machine shop methods more efficient.

If was me I'd JBW on some tabs inside tank to hold and align evenly the piece laid back on and trial error grind or add JBW till sets in just right, then JBW the seams to fix and seal and set up 24 hr. That alone would work as permanent as anything. I'd seal whole insides with JBW if it flowed well enough to do in a life time, w/o opening the tank : (

Hmmmm, I just read your opening post, no mention is made of what damage is being repaired or if just preventive sealing for new fuel. If just preventive sealing, like I and many others have done on FB and steel tanks, the two part epoxy or couple other sealers recently available will do the trick. Once good layer should work but some will do a 2nd or 3rd, if bad areas to fix. Most the etching - cleaning parts of kits are intended for steel rusted tanks not FG.
Acetone will be a main component of them all, steel or FG.

Well. Thanks for the help, I think I have a pretty good understanding now. I'm sure there will be more questions to come as the job actually starts. Now...just to find a good resin. I'll try some places like Carbonfiber suggested

I also have one more question , is a novolac resin with high styrene levels better or should I be looking for low styrene levels, or does it matter??

Thanks

If you are sealing the inside of an existing tank you need a solvent free product, as solvent evaporation can be affected if the resin is inside a tank, and this can compromise proper cure.

To be honest though in relation to a popular tank such as the GRP Norton types, I find it hard to grasp why no one is producing fuel resistant higher quality copys of the originals using the proper materials and production techniques?

The only reasons I can think of is that most producers dont have much idea of whats causing the problems with GRP, secondly they are not making enough to use a 205kg barrel of resin before its use by date, but most likely they are not willing to pay almost double for a resin system that is 100% resistant to modern fuels!

I contacted the Norton Owners club here in the UK regarding issues with GRP tanks, but my emails were ignored, so I guess there might be someone already making usable replacement tanks in the UK, and maybe US owners might want to look into this?

Carbonfibre said:

mattthomas4444 said:

Carbonfibre said:

If you are an experienced laminator then separating a tank and bonding it back together is certainly a realistic option, but if not then this isnt a simple job as suggested on here, and may well result in a scrap tank!



Carbonfibre,
Thanks, judging by your name, I think i will take your advice, however I really would like to do it myself, im trying to save as much money as possible, and getting someone else to do it would probably cost the same as a new steel tank. As far as the novalac epoxy goes, i searched it a bit, and found many different types, is there a specific type that you recommend? Also, what types of GRP should i use, sheets of it or actual individual fibers? Should i use a mat (Chopped Strand Mat) of GRP, then follow with "woven cloth" or "glass fiber tissue" to add a smooth finish? Also, should i sand in between layers, or leave it? Finally, what should i do for prep work, I dont quite know what crushed glass would do. Sorry for all the questions, I am not too familiar with F/G.
Thanks a bunch,
Matt

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Unfortunately the content of this thread provides a very good example of the seeming lack of understanding of the problems likely to be faced by anyone using alcohol bearing fuels in old type GRP tanks, and how to overcome them!

I will provide some accurate guidelines here, and some points on resin selection which are supported by manufacturers chemical resistance data:


4) Cutting open tanks: If tanks are to be sectioned to add chemical resistance layer, ideally the interior surfaces need to be blast cleaned using a relatively gentle media, scoured with acetone, and chemical resistance layer applied to all interior surfaces in the form of one layer of 100 gsm csm, followed by synthetic veil resin rich layer, all laminated using a novalac epoxy resin. The sections ideally must then be bonded together within the time period available to achieve primary bonding. Finally the bonding line then needs to be sealed completely through the introduction of a small quantity of thinned novalac epoxy, and the tank manipulated to ensure bonding area is fully coated.


.

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I was under the impression that most (all?) CSM had a sizing/binder that was specific for use with polyester resins and not epoxys? The polyester dissolves it allowing the fibres to move relative to each other to conform to the base contors.

Hobot, please dont glue a tank together with JBW, if you do it is very inportant that you tape the the joint from the outside. The JBW butt joint will be no where near as strong as the tank and the actual bond betwen the JBW and the tank will not be all that strong, a mechanical bond only.

Cheesy I'm alert to your warning but also experienced with JBW and can guarantee an all around tank seam with JBW will be stronger at the seam than the base fiber glass. Especially if the FG edges left rough as can be and still fit together. Resin is way more brittle than JBW if no fibers in it, such as in a tight seam. Dont get me wrong carbon and you are giving best advice there is for tank repair as needed if it was an airplane but JBW is more than plenty for the light loads and chemical resistance of mere cycle tank.

I've fixed boats and transoms so know about the wider and wider over lapping of fiber sheets over seams and corner bracing. Just don't think its needed in gas tank but for covering big area to contour before paint. Sanding FB to shape is terrible nasty task and exposed fibers need to be resin over before finished.

Again I'm confused if the subject is repairing an injured - decayed tank or just preventive sealing. My interest in opening a tank is to place fuel slosh baffles and metal plates so magnetic tank bags can stick on. I'd use JBW to hold pieces stable on roughed up surface, not resin and fibers. But either would do it.

Well hobot,
I am mainly interested in preventative measures, and I also am wondering what the tanks like after 35 years or sitting around.

Ok unknown inside but not obvious damage. I say over kill beyond just sealing with the good stuff available now, but I can relate to no peace of mind until going all the way in to know for sure and solve it for peace of mind a long ways from home.

The binder in CSM does need to be specific if you intend to use epoxy resin systems..............powder bound CSM must be used with epoxy resins, and use of CSM intended for polyester systems can mean major problems.

Use of any epoxy product based on "bisphenol a" is not to be recommended in relation to long term immersion in fuel. Not sure whether JB weld is "bisphenol a" based or not, but i would imagine so, as the far more chemically resistant novalac systems are more costly to produce.

Thanks carbonfiber ill try to get the most fitting CFM for novolac epoxy resins.
Hobot, I know it's a bit excessive but I just want to do everything I can to protect my engine, carbs, etc from gumming up, I'm on a tight budget and a new tank would be a real hit to the budget.

Matt, I'm not misleading you on the most efficient cheap 'quick' long term preventive to use Caswell's 2 part epoxy or the Hirsch sealer and double coat it to be twice over protected. I being such a risk taking fella only used one thick layer in Peel's IS tank, 7 yrs ago and a couple of tank dinging crashes, one that broke through to splintered glass fibers on outside but stayed intact sealed on the inside. I believe the Caswell epoxy is what strengthened the tank that become the fork stop - after fork broke past the non epoxy backed up merely welded stem stop tab.

You can use light and dental/angled mirror to get good enough view inside to see if anything flaking or bubbling up, likely not. Add up the costs of the aircraft level process and likely about half cost of new tank. Whether re-glassed or just sealed, either way you should not leave boozed fuel inside too long as can cause water layer over time and clog and corrode carb metal even if no tank bother.

Its takes a good hour or ~ 4 cigarettes of rolling tank to get Caswell clear epoxy to set up stiff with similar thickness all over and not flow into a puddle.

Any unmodified epoxy is simply too brittle to work properly as a tank sealant! Hence my several suggestions to use some sort of binding agent to increase the durability of the cured film.

Ok Carbon I can't contest with your level of epoxy resin knowledge. I've not yet heard of Caswell failing that was put in thick or in layers. Followed other Brit lists last 12 yr with stories of dissolved tanks up to seizing engines but solved once Caswell'd. I'll quizz them for survey as Caswell topped the sealer list a decade ago. I was very pleased with the shock compliance of Caswell's sealer on the front of tank crush impact I was sure had cracked all the way through but didn't. Only had to blob bondo in hole and build up the crushed in contour and paint. Short of tank crushing impacts I don't think brittleness in sealer matters in such rigid thing as small gas tank. If you know of cases Caswell failed when properly applied that'd be worth hearing about to warn off everyone - including me. FG IS tank weighs about the same 6 lb as a steel Roadster tank, sure would like to keep it and spend on other stuff.

i've bumped enough pure fiberglass hulls and thin wood ones FG cloth covered in layers to know what brittle means to resin/cloth implacted on a board area.
Ugh one was a little race hull made of 1/8" door veneer with only light layer of Fiberglass, it hit a post just covered by hi tide to completely shred the bottom in long strips of wood and flailing fibergass but at least got grounded with engine still out of water. Classic views exist of Corvettes impacted to just dust and fibers.

Carbonfibre said:

Any unmodified epoxy is simply too brittle to work properly as a tank sealant! Hence my several suggestions to use some sort of binding agent to increase the durability of the cured film.

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Carbonfibre,
When you talk about binding agent is that the same as a resin. Or is that the way the glass is actually held together before resin is added? (powder etc.)

If you are trying to apply a thin film slosh coating inside a GRP fuel tank, and that coating cures very brittle, and the tank is subject to high and low frequency vibration, then cracking of the film is something that is very likely. Increasing the film thickness is certainly likely to make it more durable, but its very difficult to make sure the covering is uniform in all areas, so problems are still likely.

Some industrial sealing products use binders to increase the durability of thin film coatings, and I have used products with ceramic materials added, and have also heard of kevlar pulp being used. If the producers of tank sealers weren't more interested in the bottom line, then producing products that actually worked a whole lot better certainly isnt rocket science, and could be achieved relatively easily.

Unfortunately the complete lack of any proper testing of these products, does seem to suggest that profit is by far the most important consideration, and spending a few extra pennies to improve performance drastically simply isnt going to happen anytime soon!

Well, I have had two negative responses from novolac resin companies saying that they don't sell quantities for me. I emailed three more companies, and am waiting for a response at the start of the work week. One company did say that I would need to contact the tech. help section, and they will tell me if the resin holds up to ethanol, then contact a distributor to see if they can sell me the right quantities. But for now I'm just hoping that someone can make a deal with me, and hopefully the prices won't be too high, I've started to worry about the high prices of novolac resins!!

Novalac is more costly than much more common bisphenol a products, but is a great deal cheaper from an industrial manufacturer than someone like Caswell, who appear to thin down industrial resins to allow easier application by those who are not familiar with composites (and of course to increase profits!).

If you have no luck finding a manufacturer who can help, then see if there is anyone producing "Rib" type powerboats close to you. Some of these have fuel tanks incorporated into the hull itself, and obviously the lay up used has to be 100% proof against any fuel likely to be used.

Alright,
Thanks for the tips, I am fairly land locked, however i doubt ill have trouble finding a boat manufacturer close to me.

If i do get an industrial company to sell me some, Ill report back incase some of you guys are interested in the company.