Adding lightness through sanding, Questions about body repair and paint

[TurboFource]

Interesting topic 

[dakazman]

Interesting topic 

             
   
   If you really want to learn more visit :

   https://www.fibreglast.com/category/Learning_Center
 
Dakazman

[GavinT]

 but when it's made they use an additive to bind the fibres into that sheet of matting - whether it's woven roving/CSM, veil, or whatever.

It's my understanding that woven cloth doesn't have any binders at all and relies on the fact that it's woven which kinda holds it together.

How is CSM marketed in the UK/Europe? Here in Oz, I couldn't find any CSM with the powder binding and as far as I can gather, the situation is similar in the US.
I'm just wondering if they sell both over your way or just sell the powder binder version and don't include the binder in the description at all . . . which would also be logical.

Harking back to that video, if you scout around YouTube, you'll find other videos demonstrating CSM with epoxy pointing out it's nearly impossible to work around, say, a right angle form. The glass itself kinda stays stiff, whereas with polyester resin, the CSM becomes floppy and takes to complex forms much more readily.

[My S1]

In regards to polyester & vinyl ester vs epoxy laminating resin, don't minimize the health, comfort and ease of usage factors.  The styrene fumes in polyester and vinyl ester not only smell like hell but they will kill you sooner than the epoxy gases.  Epoxy, while considerably stronger than the ester resins, also afford one longer kick-off times which makes it much friendlier to work with. Much less stress and if you are going to vacuum bag, you have an hour or so to work with. Set times are easily adjustable. Cloth is always a superior choice over matt for too many reasons to list.  I believe that every cloth (fiberglass and carbon) that I have ever used, did not contain styrene binders.  That's my two cents worth...

[gideon]

I agree with My S1. 

Just don't use CSM.  Use cloth or some loose chopped fibres mixed into resin.  Or both.  Add some peel ply and vacuum bag the repair if possible.  I found some lightweight, fine weave glass cloth that would make a nice finishing layer to minimize the potential for print through

https://fiberglasswarehouse.com/collections/fiberglass-cloth/products/1-5-oz-x-50-wide-fiberglass-cloth-style-108

One youtube channel I like for demonstrating practical composites repairs and stuff is the Duracell project.  In this clip he repairs the sheer clamp.  It's a bit heavier duty than a Lotus bodyshell repair but some of the procedure would be similar.

https://youtu.be/NybZZF6-Gk0?t=938

[dakazman]

  Gideon and S1,
    Do you use epoxy for spot repairs or over an entire panel? have you got a year after shot of the repair?
  I'm always looking for an easier way to do the job and make it look better than OEM.
 This is an ongoing discussion for our group, corvettes, boats and they can't decide. I've seen my experts set fire to some resin repairs that they were rushing. vacuum, nice repairs of aircraft structures are mandatory. We are just trying to get a professional finished look.
 golden gate also states that there is no structural component to the body.
 Dakazman

[gideon]

Spot repairs or an entire panel.  Either way.  I haven't even started on bodywork yet, let alone have a one year after photo.  All my practical experience comes from fixing boats.  I'm actually fixing one right now, but I guess that would be off topic.

[dakazman]

Spot repairs or an entire panel.  Either way.  I haven't even started on bodywork yet, let alone have a one year after photo.  All my practical experience comes from fixing boats.  I'm actually fixing one right now, but I guess that would be off topic.

  Boats
  Been there,  Lets see upstate NJ ... Lake Hapatcong ?  I lived in Jersey, 30 years, which was all my life at the time.
 Dakazman

[GavinT]

… Regrets, I've had a few ...
Below is a pic before I knew any better - woven fibreglass cloth which printed through my then new paint job. 

Here's a video (approx 12 min) illustrating some common issues working with fibreglass for the uninitiated.
While the demonstration pertains to laying glass in a mould, there's plenty of info relevant to the common type of repairs on a Europa body.

https://youtu.be/ZfRBgvXRpY8?si=sWLFggk1oF-hQ5N2


The same people show how to replicate a 'EUROPA' badge in this vid (8:30 min). How cool is that!

https://youtu.be/WmDfJicrrYo?si=0u0GGnF5LXg1d7wp

[Dilkris]

GavinT above - what color was the paint on the car? That looks like woven cloth that is lacking in saturating resin.

[GavinT]

'Twas green as per my avatar. (pic below)

Re the woven cloth . . dunno exactly.  It may well have been scuffed during the extended time it's sat idle (and shipped around the country) but it is sufficiently saturated. And don't forget, the body was also sand blasted, so that may be part of it.

At the right-middle of pic you might observe an oversaturated 'lake'. It's not all that bad, but does reflect the nature of the task, i.e. applying a thin layer of material on a preexisting hard cured panel.
At the time, both anomalies were rectified during the paint prep stage and a few small furry areas don't present an issue.

But that's not the actual problem, of course. The woven cloth stopped the crack reoccurrence just fine, but it printed through worse than lycra bike shorts. This all showed up maybe a year or so later.
In my case, the cloth will be coming off, of course.

All that might explain my experimentation with thinned down resin in a quest to avoid an over saturation of the veil/tissue.

Cheers,
Gavin

[BDA]

Without going into the history of my car, I had a buddy who was in partnership in a fiberglass shop cover my car with thin cloth. According to him, he tried everything (fillers and sanding) but the cloth still printed through the paint. I imagine you could prevent the printing by covering it with veil but I don’t think cloth belongs on the exterior of a car in the first place.

[Dilkris]

According to him, he tried everything (fillers and sanding) but the cloth still printed through the paint. I imagine you could prevent the printing by covering it with veil but I don’t think cloth belongs on the exterior of a car in the first place.

Some years back, I heard, personally, this argument used by one of the UK's renowned automotive glass fiber specialists - he maintained that you cannot create a stable base for the various paint processes on a car without first covering,(encapsulating really), the car with veil.
In my ignorance I am hoping that glass fiber technology and more to the point, available products, have now developed and advanced to a level whereby this process can now be avoided.         

[GavinT]

With my car, the cloth print through came and went, to some degree. This wasn't something I watched closely or thought about much at the time; I was just annoyed. Only now since the subject has come up do I recall our own D'man who made a number of comments with respect to changes in paint surface characteristics on his car.

He was noting his car changed before your eyes (or words to that effect) and I think he said it was related to hot sunny days. His car is black, so that may exacerbate the phenomenon - dunno. D'man lives in Florida (I think) which is a similar climate to mine, so that might be something.

Perhaps the resin expands and contracts differently than the glass strands in the cloth on a hot day and it becomes more obvious because the cloth pattern is more distinct & recognisable than, say, CSM.
Hopefully, D'man might chime in.

[Kendo]

The resin is also different thicknesses on the top of a cloth strand (wrong term...) versus in the valley between strands. I suspect the mat has less variation across the surface.

As an aside, while reading about surfboard building, where they used cloth, some finished with a surface layer of micro-balloons in resin, to fill in that weave. I don't know how effective it would be.