Bodywork Repairs

[murramor]

Have you worked with resins, do you need procedure info

The last time I did anything worth mentioning was 35 years ago when I made a couple of car seat shells so my experience is very out of date.  The few times I have mixed resins since, I have had very variable results so I have been looking on the Lotus forum for hints.  They seem to recommend the West system

 http://www.westsystem.com.au/west_system/

What attracts me is their dispenser system so as to get the proportions correct as I feel this is an area where I have gone wrong in the past.  Either too much or too little catalyst.

One of the cracks on the rear skirt had been 'repaired' by the previous owner and I was able to pull the patch off by hand as it had not bonded at all well.  This got me thinking that I had better get up to date with current thinking and find out what are the pros and cons of the various materials.

Also I have one small area of stress cracks which I intend to fix with tissue and resin after grinding away the gelcoat.  Stress cracks worry me as I have not been terribly successful with repairs to my Lotus. (again 25 years ago). The repairs have tended to shrink over time and become visible.  I have thought to avoid this problem by waiting a month or so before applying a final coat.

[bist]

Dispensation can vary by manufacturer,but common for polyester is on 100g resin 0.5g or 0.5ml of accelerator (usually already mixed) and 2g or 2ml of hardener. The temp cant be below 15C, the ideal is 20-23C, if below the accelerator can be raised (hardener not) and vice versa.
Westsystem site have pretty much everything you need about epoxy and working with it.
For cracks, for first layer, just to fill crack, I use glass cutting or powder or ash, after, another two thin layers of twill.
After epoxy you dont need primer, chemicals dont etch it, just good sanding. Polyester gets weakly stick to it to. At the end you can put plastic foil, expel the air and you will get nice surface. If there are some air hole after, fill them with resin- air bubbles contour after few month if is used some filler.
The stiffnes mostly depend on air between layers and in fiber coating, it must be complet transparent after applying.If its very stressed spot,with epoxy you can use carbon fiber and youll get most you can.