Lotus Elan

Fiberglass *MAT* and Epoxy

PostPost by: JonnyPlus2 » Sat Jun 17, 2017 12:49 pm

I think that you're correct about the CSM.

It *is* worth noting that one of CSM big advantages in a production situation is that it can be sprayed in using a fancy gun whereas cloth requires hand work. So I think that CSM was used by Lotus' suppliers to keep costs down. I don't think that this means that you *have* to use CSM to repair them. I'll experiment with CSM in about an hour or so . . . and . . . . I'm one of those people who has to learn by experience . . . . so that's what I'm going to do. The other catch is that I'm using Epoxy which makes CSM a bit of a pain to work with.

Thanks for your straight talk, I'll report back when I'm done.

"Good judgement comes from experience . . . experience comes from . . . bad judgement" - Anon :lol:
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011

PostPost by: alan.barker » Sat Jun 17, 2017 1:25 pm

Sorry i have been using the wrong material names, here is the correction
1. lightest TISSUE
2. medium ROVING or SHREDDED MAT (not chopped strand i got mixed up)
3. heaviest WOVEN MAT
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
alan.barker
Fourth Gear
Fourth Gear
 
Posts: 647
Joined: 06 Dec 2008
Location: BRITTANY FRANCE

PostPost by: c42 » Sat Jun 17, 2017 2:56 pm

Of course you could make life a little easier and use polyester resin.

John
User avatar
c42
Third Gear
Third Gear
 
Posts: 288
Joined: 10 Sep 2009
Location: Rugby, Warwickshire

PostPost by: Esprit2 » Sat Jun 17, 2017 4:19 pm

JonnyPlus2 wrote:I'm keen on cloth as it gives an inherently stronger repair as there is less resin in it.
Woven Roving (ie, 'cloth') is stronger, but the weave pattern can imprint through to the surface and be visible through the paint. If you start with a bare mold to make a new part, laying in a few layers of matte first, then a layer of woven roving 3+ layers deep can imprint through to the surface. Yes, 'tis true.

For structural composite panels, you're right, woven roving can produce a stronger part "IF" you're smart about how to orient the fibers. If you're laying up a composite fuselage for your homebuilt aircraft, use woven roving. But for cosmetic panels (car body panels), matte is better since it will not imprint any pattern thru to the surface.

If you're putting another layer on the inside of an old Lotus panel, then it's probably not a big deal what you use, other tan matte will conform more easily around abrupt surface contours... like around a bobbin (then wrap it with some linear roving.

However, if you're making any external repairs, like fixing stress cracks, then avoid woven roving and veil (very fine, 0.5 to .75 oz woven roving). Instead, use matte or tissue (0.5 - 0.75 oz matte).

Off Topic, but...
A friend of mine used to own a Countach. The body was mostly metal, with a few graphite pieces mixed in... like the front bonnet. Over time, the weave would imprint through, and Countach fans consider the weave pattern a badge of honor... proof of the car's originality. One time he had some body work done to the front... nothing that involved the bonnet. The body shop took it upon themselves to do him a favor while they were working on it, and 'fix' that crude bonnet. It came back looking like a mile deep black mirror. Perfection. Their hearts were in the right place, but they really ticked him off... he pissed & moaned that it would take years for any hint of that weave pattern to come back.

Regards,
Tim Engel
Esprit2
Third Gear
Third Gear
 
Posts: 236
Joined: 02 Apr 2008
Location: Twin Cities, Minnesota, USA

PostPost by: JonnyPlus2 » Sat Jun 17, 2017 10:53 pm

Well I managed to make it work by using Tim's advice. I put in a tablespoonful of Ace Tone (great name for an amp or a band) in with the epoxy mix and let the pieces of mat soak in epoxy for 15 minutes. The mat wouldn't follow the contours very well but I kept at it until it started to set up and then I was able to persuade it to stay down. I had to come back every 5 mins and re-persuade it but eventually it stayed down.

I think part of the issue here was that I was putting the mat over an outside corner (bobbin in the rear suspension tower) so it had a strong tendency to fold up and away from the original F/G. Next I'm doing a floor bobbin so that will be inside corners. I'm hoping that's easier.

Thanks much for all your help and suggestions.
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011

PostPost by: alan.barker » Sun Jun 18, 2017 6:33 am

Well done that man, like you said you just need practice.
With grp fibres wound around the outside of the Bobbin for sure it can never come loose.
How about a photo when you do the floor Bobbin but be careful not to get resin on the Camera :shock:
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
alan.barker
Fourth Gear
Fourth Gear
 
Posts: 647
Joined: 06 Dec 2008
Location: BRITTANY FRANCE

PostPost by: JonnyPlus2 » Sun Jun 18, 2017 1:00 pm

Hi Alan,

I'll do my best to get pics of the floor bobbin. I am currently unable to extract photos from my camera. My 25 year sons are coming home for a visit today so they should be able to figure out how to do it.
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011

PostPost by: bill308 » Tue Jun 20, 2017 6:50 pm

IMHO, woven glass and epoxy are the wrong products to use for Lotus repairs, unless there is a really good reason to do so.

West System Epoxy is great stuff, stronger, less affinity to absorb water, and probably inert to more chemicals. It is however more difficult to work with, more expensive, and requires a much more critical/precise mix ratios, and an induction time. The other down side is that polyester should not be used on top of it.

So when should epoxy be used? I think primarily when it will see extensive exposure to water, particular solvents, or when its other material properties are required.

Woven cloth is a poor material to use on a Lotus, or boat for that matter, because it is harder to wet out (especially thicker/heavier cloth), is less conforming, and over time its weave pattern can show up in the finished surface.

There is a reason Lotus used matt and polyester resin for its products. Its economical, conforms to contours better, is easier to use, and results in a better long tem finish. Mix too much activator (MEKP) and it will cure faster, at a lower temperature, but will be more flexible, or less rigid. Mix too little activator, it will take longer to cure (although a heat lamp or other heat source may be able to bail you out) and will be more brittle. Left unprotected, polyester resin will absorb water and its physical and chemical resistant properties are not as good.

Given the choice, I always prefer polyester resin with matt. I've even had good luck with 10-yo resin in non critical applications. Just fish the jelly out and mix as usual, but have a high watt lamp handy to help the cure if necessary. I know Gary Anderson has used some pretty suspect resin in his career, check his old postings.

Bill
bill308
Fourth Gear
Fourth Gear
 
Posts: 729
Joined: 27 May 2004
Location: Windsor, CT USA

PostPost by: JonnyPlus2 » Wed Jun 21, 2017 3:03 am

Hi BIll,
Caveat: I am *not* a fiberglass maven. I'm just a regular shmuck trying to do a good job on his Lotus.

F/G repair is very different from moulding F/G during manufacture for the the following reason:
When you add a patch to a car, you will end up with two pieces of fiberglass reinforced resin (the car and the patch) that are chemically bonded to themselves but *not* chemically bonded to each other. They will be bonded to each other mechanically, i.e. the resin acts as a glue. The problem with Polyester is that it's no hell as a glue whereas epoxy is dynamite.

IFF the above is true, then patching with polyester will not make a very strong repair. You'll have two relatively strong pieces relatively poorly bonded. This explains why I've been able to pull a lot of the old patches off my car. (Everyone who has ever repaired my old nail can't have been a complete incompetent), so I think it has to do with polyester's weakness as a glue.

The great thing about the WEST System Epoxy is that you just give one pump of the old resin to one pump of the hardener through their proprietary pumps. That is, I believe, the point of the WEST System. It makes the measuring part (critical with epoxy) easy peasy.

If anyone disagrees with this, please let me know. I'm here to learn not to spout.

P.S. PIcs are coming, just have to take the last one or two and then I'll post 'em.
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011

PostPost by: Terry Posma » Wed Jun 21, 2017 4:57 am

It probably goes without saying that you should ensure that the pumps are kept clean, particularly the hardener.

A good system but you can get some awful mixes if the pumps are dirty.
Terry Posma
First Gear
First Gear
 
Posts: 48
Joined: 24 Nov 2003
Location: Australia

PostPost by: JonnyPlus2 » Wed Jun 21, 2017 6:07 am

Hi Terry,

Thanks for this tip! I had no idea. I think that the WEST people say that you can store the stuff with the pumps in!

How long do you think I should go between cleanings?
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011

PostPost by: nmauduit » Wed Jun 21, 2017 7:13 am

JonnyPlus2 wrote:IFF the above is true, then patching with polyester will not make a very strong repair. You'll have two relatively strong pieces relatively poorly bonded. This explains why I've been able to pull a lot of the old patches off my car. (Everyone who has ever repaired my old nail can't have been a complete incompetent), so I think it has to do with polyester's weakness as a glue.


I would respectfully disagree, esp. with the a priori ruling out of the widespread of incompetence in the automotive business. When the existing polyester fiberglass is properly tapered, incidentally just like the Lotus manual recommends, I am confident that the repair will last at least as the rest of the body. I understand it does take longer time to do, requires to remove components to access the rear side... and one should obviously bond to fiberglass that has kept good mechanical integrity (not full of water, de laminated or shattered).

p1040388.jpg and
Lotus manual on fiberglass repair


Then the choice of using epoxy on a polyester body, unless on very specific parts of a race car perhaps, raises more issue than it solves to my understanding...
S4SE 36/8198
User avatar
nmauduit
Third Gear
Third Gear
 
Posts: 430
Joined: 02 Sep 2013
Location: France

PostPost by: Terry Posma » Wed Jun 21, 2017 10:17 am

Re the cleaning of pumps, resin can be left for a while in the pumps, up to a month but it does attract dust and dirt. Hardener is a different matter as it starts drying within a couple of days so you need to clean the whole pump out if you are not going to use it within a week. If you use it within a week give the pump a little push first and wipe away to get rid of the scab (so to speak).

Polyester over polyester is fine as long as you re key the surface as there is wax in the resin which rises to the top and blocks the key. This is true also of epoxy over polyester (and vinylester).

Never use polyester over epoxy but the reverse is fine.

Epoxy is far more structural than polyester and thus you will get a stronger result with epoxy with less resin and mat. In boat building, polyester and vinylester are used in cheap producition boats where the added weight and softness are not an issue but in race boats or where there are strength and weight issues epoxy is always used.
Terry Posma
First Gear
First Gear
 
Posts: 48
Joined: 24 Nov 2003
Location: Australia

PostPost by: prezoom » Wed Jun 21, 2017 4:41 pm

Not sure what is available in OZ, but I am able to purchase both laminating and surfacing resin in the US. While surfacing resin contains wax, laminating resin does not.
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Tread softly in the grease mud, for there lurks the skid demon
prezoom
Fourth Gear
Fourth Gear
 
Posts: 739
Joined: 16 Mar 2009
Location: Escondido, California

PostPost by: JonnyPlus2 » Wed Jun 21, 2017 4:47 pm

Hi Alan,

Here are your pics.

img_0890.jpg and


img_0891.jpg and


My Official Photographer apparently missed the rear upright bobbin repair.
Best,
Jonny B
36/6322
JonnyPlus2
Second Gear
Second Gear
 
Posts: 108
Joined: 08 Jun 2011
PreviousNext

Total Online:

Users browsing this forum: No registered users and 3 guests