Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: dakazman on Friday,January 26, 2018, 07:10:25 PM
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Sadly Started repairing the blisters that popped up in paint. Just as it states in the lotus manual, cut out and fill in , repaint. This still holds true . Here are some pictures that document the fix.
Dakazman
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Bummer! So the big question is how do you prevent that from happening?
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That's a drag. I doubt it was a problem in your prep work, I can't imagine a more thorough job that you did. My friends who paint boats with Awlgrip are anal about humidity and dryers on their compressed air lines. Failure to do so causes blisters, they say. And you do live in ultra-humid Florida. Hopefully you can blend-in the repairs. What kind of paint are you using?
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These were all fractures deep into the glass and not blisters caused by contaminants. They were all slowly picked open and inspected , then grinded out with a dremmel . Then refilled with glass matting cut up and mixed with resin.
I'm using a base black g9900 and a clear so it is easy to match.
Dakazman
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From personal experience and everything I have read about fibreglass repair I would not choose polyester resin for repairs or alterations to existing polyester resin fibreglass. Always epoxy because epoxy sticks to polyester much better than polyester sticks to polyester. I don't know if this has anything to do with your bubbles, but I think it's worth saying anyway.
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I wanted to dig up a reference to back up my assertion about epoxy being a better choice than polyester resin. This is from the manufacturers of the most well known brand of epoxy resin in the boat building/repair market.
https://epoxyworks.com/index.php/west-system-epoxy-vs-polyester-for-fiberglass-boat-repair/
I trust what they say.
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That’s all true.
Still sometimes you want the flexibility that the polyester gives . The examples I can only give we’re done 18 years ago , have about 400, 000 miles on it and still no hairline cracks .a full glass nose installed removing the factory neoprene bumper and side skirts molded into the entire lower section and up the forward side of the rear wheelwell. Boats are a different animal and probably need the higher bonding adheasion . These blisters were in an unrepaired area and I see no reason to use a higher cost product for such a small repair .
Dakazman
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Actually, epoxy resin is more flexible than polyester - from the west system article. "epoxy offers 3.5% to 4.5% tensile elongation at failure compared to 1% to 2% for typical polyester resins". Epoxy also shrinks less on curing.
I completely understand that if you already have some polyester resin, and it's a small repair, then you're not going to rush out and spend money on a more expensive product. And, yes, polyester fibreglass lasts incredibly well. And, yes cars aren't quite the same as boats. But that all being said, epoxy is still a better choice than then polyester for fibreglass repairs. I know from past experience that it is much easier to get a strong mechanical bond with an epoxy resin like west system, than with polyester resin. The additional cost of the resin is typically small compared to the time and effort involved in making a repair, which is why I use it. Though, it does help that I already have some in stock for boat repairs :).
For small repairs, there is an inexpensive repair kit they sell with resin sachets, fillers and some other useful bits and pieces. Here's one source
http://www.fawcettboat.com/pc_product_detail.asp?key=DA21D3FB9D4044F4A70CD347F973AD66
I'm only saying this now because I really think it is good advice, supported by a lot of practical experience, and I would like to pass it on. I'm sure your repairs will be fine, but maybe for somebody else it will pay to use epoxy resin instead :).
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Very well stated, Gideon!
You learn something new every day , which I have.
Dakazman
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G’day, dakazman,
I don’t know if you’ve tried it but there’s a commonly available product colloquially known as “kitty hair” . . brilliant stuff for those little annoying repairs.
It consists of fine fibreglass strands mixed with a polyester base with a similar constancy to common polyester body filler and uses the same catalyst paste.
FWIW, the method I’ve used is to dab in the required amount, cover it with cling wrap and give it a quick roll using a wallpaper seam roller.
Wait till it goes cheesy, then, using a sharp blade, slice off anything proud of your masking tape.
Hope that helps, & cheers,
Gavin
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[...] because epoxy sticks to polyester much better than polyester sticks to polyester.[...]
True enough . . . polyester doesn't stick to epoxy brilliantly.
This is probably not a big issue either way, but with say, potential future repairs I wouldn't want to confront sheathing an engine cover (for example) with tissue using polyester resin and find out months later that it's delaminating due to sub-optimal adhesion and being out in the hot sun.
More grist for the mill . .
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Thanks GavinT
Just a little stuck in my car ways a bit but open to new ideas.
The VHS tape may give it away a bit but this is as my bible.
I did like your repair method and use it on repairs not depending on gravity. ( overhead)
Lol. Tape in place , roll .. and let sit.
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The VHS tape may give it away [...]
It does . . you've lost it.
I'm kidding . . :FUNNY:
Then again, I might confess to using my fathers wood chisels from the 1920's!
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GavinT , it was painful to watch 25 years ago , the worst thing is I transferred them to DVD .
I can send you a personal copy 😀😩.
Btw , how does density of the epoxy mix compare with polyester?
Dakazman
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This is from fibreglast.com a development company.
Selecting Resin
Resin selection is based on fabric compatibility, service conditions, and the desired characteristics of the finished part. There are two common types of thermosetting resin to choose from: epoxy and polyester. Moldmaking, molding, laminating, and casting operations can be performed with either system. Epoxy is the higher performance and higher priced system. It is used in weight critical, high strength, and dimensionally accurate applications. Polyester resins are less expensive, offer more corrosion resistance, and are more forgiving than epoxies. For this reason, they are the most widely used.
Vinyl ester is a third resin option, often described as a cross between epoxy and polyester resins, as it falls between them in price and handling characteristics. It offers excellent corrosion and abrasion resistance, so it is well suited for applications like chemical storage tanks.
Certain resins are not compatible with all fabrics. For instance, Kevlar® often exhibits adhesion problems, so epoxy or the highest grade polyester should be used. Also, fiberglass mats have a polyester soluble binder. Epoxies can dissolve this, and should never be used with mat. Check material compatibility thoroughly when designing.
I believe these cars are polyester base matting . That is also why I chose polyester resin.
Dakazman
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G'day dakazman,
Reckon I'll have to stumble along without a VHS tape, but thanks for the thought. :))
Not sure what you're driving at re "density of the epoxy mix compare with polyester" ?
The point you make about chopped strand mat is a fair one. They're all lightly pre-impregnated with polyester resin and unsuitable for Epoxy. Also, it's best to avoid woven cloth on surfaces that are going to have a finish painted surface. The cloth weave will print through and become visible under the paint. Ask me how I know. Oooops . .
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Yes the cloth weave is patio furniture quality.
Not to rehash epoxy over polyester ... we agree epoxy is better.
However,
The first patent for epoxy resin brought to market date 1984 .
Our cars are 60-70 ish . How we’re all those cars repaired?
Dakazman
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I believe these cars are polyester base matting . That is also why I chose polyester resin.
Yep, I couldn't see them being anything other than polyester resin, and probably cheap ones knowing Lotus ;)
Personally I'd stick with polyester resin as well. I remember being told that epoxies were "better" in that they had less shrinkage and therefore held out better on repairs, but I'm not totally convinced it's an essential feature. I don't get much in the way of sinkage on the repairs I've done using plain polyesters. When you think of the usual stresses on bodywork over mileage and the thermal expansion/contraction you get from +30C to -20C then I think I'd prefer that all the resin has exactly the same properties.
But if you're building a race car and want to have bodywork 1/16" thick or want to use carbon fibre then yes, I can see the value in selecting a different resin.
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Epoxy dissolves the binder used in chopped strand mat, so you'd have a problem if you tried using epoxy with fresh chopped strand mat. It's not a problem any more once the original mat is set in resin.
Two arguments against epoxy for repairs that hold up are 1) price and 2) polyester doesn't stick well to epoxy. So, if you think you might want to use polyester in the future then avoid epoxy. Personally, I plan to always use epoxy.
The comment about corrosion resistance from Fibreglast.com is a little puzzling. I was not aware of lack of corrosion problems with epoxy, but I guess it depends what chemicals we're talking about. I found these tables of corrosion resistance, which unfortunately aren't easy to compare
https://www.engineeringtoolbox.com/chemical-resistance-epoxy-d_786.html
https://www.engineeringtoolbox.com/chemical-resistance-polyester-d_784.html
Luckily, and this is important, I have learnt that both epoxy and polyester are resistant to beer.
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UV resistance, that's the other thing. Epoxies need to be protected from UV light. Polyester resins are much more UV resistant.
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Beer good😜
Even with we car and rear view camera she still backs into a pole.
More bodywork for me😓😢
Dakazman
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More bodywork for me
Dakazman
Practice makes perfect! (Practice on the Honda, save the perfect for the Lotus) ;)
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At this point yep
At a breaking point . Four daughters are killing me😀lol
All princesses.
Dakazman
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Four Daughters....... you are a saint!
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Two arguments against epoxy for repairs that hold up are 1) price and 2) polyester doesn't stick well to epoxy. So, if you think you might want to use polyester in the future then avoid epoxy.
Yes, but there's also arguments that are more to do with what's practical.
If epoxy is chosen as the preferred resin, then one is comitted to adopt an epoxy based system thereafter due to the polyester -> epoxy adhesion issues.
For example, one would be precluded from using the commonly available chopped strand mats.
One would also need to use an epoxy based filler to replace the typical polyester based 'Bondo' or the like.
And as mentioned previously, future repairs would likely be problematic.
Unless you know all the epoxy repaired areas going in, it's a crap shoot. You can't visually determine which areas are epoxy and which aren't.
IMHO, it's not so much the narrow question of which resin is "better", but more the wider perspective of what's most suited.
There's a plethora of chopped strand mats, fillers, fine skim fillers and spray polyester fillers all aimed at a polyester based repair for the automotive industry. It's all a well trodden path, and compared to epoxy based systems, far cheaper.
I'd have to see something very compelling to ditch that well worn path, I reckon.
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Gavin,
I had experience long ago (I'm talking late '80s) of poor adhesion from polyester resin while repairing a boat. Likely my technique, preparation, etc. wasn't quite right. Since then I've used epoxy resins and very rarely had adhesion problems. You can get a good bond with polyester, but my batting average is higher with epoxy.
I choose woven or knitted cloth over chopped strand mat. Longer fibres make a stronger composite.
You don't necessarily need a lot of different products. You can mix additives into the epoxy for different purposes. Microballoons for a lightweight, sandable mix. Silica thickener for a dense, hard, non-slumping mix. Milled glass or carbon fibres for tensile strength, etc.
But, to each his own. I have my preferences, you have yours. So be it.
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G'day gideon,
My apologies if that last post came across as combative. It wasn't intended to be but can see now that it might be interpreted that way.
And certainly, our own experience tends to guide our thinking . . as well it should, so no harm and no foul as far as I'm concerned.
That said, I'm curious as to the materials you intend to use. My experience with woven cloth (even the really fine stuff) is that the weave pattern just prints through and is visible under the paint.
And for what it's worth, I'll add that adhesion problems are not unknown in an all polyester repair, either. I expect we've all seen them.
It's important to remember that polyester lay-up resin contains wax. During the curing process, that wax floats to the top of the laminate but is essentially invisible.
To put a further layer of polyester resin over that lay-up without abrading the the top layer (to remove the wax) is inviting a de-lamination.
As an aside, I've toyed with the idea of making a windscreen surround to convert the Type 54 into the Type 65 for the purpose of adopting the much neater bonding in of the windscreen.
My intention would be to make the surround using polyester resin as a separate piece and use epoxy to glue it in.
Epoxy would be far more appropriate for the gluing, I reckon.
Cheers,
Gavin
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Quite a busy thread here on resins. Put in my pennyworth from experience.
1) Epoxy is much more difficult to work and hates tight bends, if you don't believe me try before you use.
2) Epoxy is stronger, more expensive, takes longer to go off, and bonds well to polyester
3) Polyester will not bond well to Epoxy, bondo etc are all polyester based so will not bond well to Epoxy.
4) Polyester will bond well enough to existing polyester if properly prepared for repairs so why use Epoxy
On blistering. the top layer of any exterior repair that should be painted should be tissued with resin to provide a top protective layer that seals off any glass fibres, to in effect replace the gel coat. Open fibres will absorb water by capillary action, so keeping the exposed body dry is important.
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Thanks buzzer, that pretty much sums it up!
Now , today marks a milestone that all my tools are under one roof.
40 years in the airline industry are over. Not retired yet but being pushed in that direction.
Dakazman
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One more nail in the coffin of this resin business: I have been told, by people who work with fiberglass a lot and at least SOUND like the know what they are talking about, that a polyester/polyester bond is greatly improved by not only mechanically roughing up the mating surfaces (sanding) but also by "reactivating" the polyester by wiping down with styrene solvent, and NOT acetone. (Acetone will weaken the bond, or so I'm told.) https://www.jamestowndistributors.com/userportal/show_product.do?pid=57891
In fact, this company is very knowledgeable about all things fiberglass/composite and has just about every kind of resin, solvent, filler and reinforcement you can imagine (and no, I'm not on their payroll, just found them easy to work with).
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I also did a little digging into this a little more and found some interesting reading on The MSDS Sheets on this epoxy stating under personal protection to leave contaminated clothing at work.
Lol, how bad can it be. So far this product is a slight carcinogenic to lab rats .! No danger to humans.
Dakazman
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Oh boy, I was ready to let this topic drop, but now I've just got to stir the pot a bit more.
Buzzer - what do you mean about epoxy hating tight bends? I don't understand that.
Surfguitar - I'll add my vote of support for Jamestown Distributors. That where I get my epoxy :). I'm sure you'll get good advice there. But - I don't see any nails in any coffins, there are some pretty good reasons to prefer epoxy.
Dakazman - I'd say try to avoid getting any epoxy on your skin, wear gloves etc, but don't panic if you do - just wash it off.
BTW - this feels like a thread hijack. Should this discussion be moved to it's own thread?
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Dunno about the "hating tight bends" thing either.
In my experience the tight bends issue is related to the fact that the glass itself tends to be springy . . usually far to springy to go around an external 90º bend, for instance.
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On the tight bends and epoxy. Polyester is easier to work and allows you to lay it better into profiles. Epoxy doesn’t seem to have the same “wet” adhesion so it allows the glass to delaminate as it tries to move back to its original flat state. So epoxy is more difficult to work. Easy on flat surfaces. Hope that explains it better.
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This company has help in all my needs for several years, these are some of the answers to resins.
As an aircraft mechanic for airbus , Boeing and McDonald Douglass in all heavy jet maintenance my experience is to inspect glass panel , remove and replace. The glass shop does all the fabrication and repairs . So I would just like to add this site as a learning tool.
https://www.fibreglast.com/product/about-resin
Dakazman
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This is a great learning guide from the experts. I am not affiliated to this site in any way .
Maybe we can ask them to be a vendor?
Dakazman
https://www.fibreglast.com/product/fiberglass-repair-composite-repair/Learning_Center
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That looks like a one-stop shop for all composite projects. It made me think about the story of John Britten building his amazing motorcycle (including wheels) with carbon fiber yarn (at least this documentary implies he only used yarn)! (https://www.nzonscreen.com/title/britten-backyard-visionary-1993). Would anybody know how one would use yarn?
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Very impressed BDA , amazing story.
Did some more research and found this link from John Bollinger on repairing fiberglass.
http://www.lotus-europa.com/manuals/lotuswest/00BI002.html
Dakazman
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I thought I would share my version of the straight-exhaust-through-the-trunk-space solution. Half a trunk/boot is better than none.
I bought a new trunk tub from rdent.com and cut out the space where the muffler goes through it with 2 inches of clearance. Next, I bent a piece of aluminum in a wood frame to the shape of the new trunk tunnel to make a mold and laid-up fiberglass (PVA mold release, black gelcoat and 3 layers (2 would have been plenty) of 1.5 oz chopped-strand-mat (CSM) in polyester resin) to make the tunnel panel.
After trimming the panel to fit the opening in the tub, I bonded it in place on the inside of the tub with a fillet of black Pro-Set thixotropic epoxy in keeping with the theory that epoxy sticks to polyester better than polyester, as discussed earlier in this thread. After the fillet set-up I ground a radius on the outside of the tub/tunnel joint and glassed that over with 2 layers of fiberglass cloth and West System epoxy.
The final step was bending up an aluminum heat shield to deflect some of the radiant heat from the muffler. Aluminum stand-offs (3/4 inch) create an air space between the heatshield and the tunnel. Stand-off screws have hi-temp threadlocker to prevent them from rattling loose. Still, I won't be hauling any chocolate in the boot. It's going to get pretty warm in there.
I still have to relocate the swirl pot the PO placed in the way of the tub (!), but at least I’ll have enough room for a small piece of luggage in case I want to take the wifey on an overnight somewhere.
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Nicely done, Surf! Not at all like the chisel and file work I usually do!
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Hey surf ,
Great job , the work you did looks seem less, and well layed out . It should do everything you designed it to.
Btw...BDA probably does not use chisels.lol.
Dakazman
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Ok, I don't use chisels on fiberglass! But on metal... ;)
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Actually, I confess to using a chisel a lot to fight back errant resin drips and globs of glass fibers. I won't even go into the monumental screw-up of my first over catalyzed gelcoat failure. The end result may not have been as easy as I apparently made it sound.