Fiberglass Tissue

[bill308]

It's been reported that some quality restoration shops cover the body skin with a fine fiberglass matt, sometimes referred to as tissue. I like the idea of this method as it helps tie the surface together, especially after repairs, with a uniform surface and that may inhibit the return of minor stress cracks that go undetected. It also suggests the possibility of effectively dealing with pin holes and other defects uncovered by extensive grinding, that one may not want to use filler on. I also don't want to change the thickness of the glass body or ruin character lines that I've worked hard to establish, hence it must be pretty thin and able to conform to compound curves.

In the US, matt is identified by its weight per square yard where 1.0 oz matt literally weights about 1.0 oz per square yard. In Europe I believe they refer to it in gms per meter but I could be wrong.

At home I have 0.3, 0.5, and 1.0 oz weights. I've noticed that the really light weight tissue is relatively stiff for its weight, presumably to enable handling with out falling apart. I found this stiffness can cause issues when trying to make it conform to compound curves.

What weight matt is used to tissue a body?

Bill

[gerrym]

Bill, I've used tissue at 30g/m2 (sorry don't have conversion to hand but I'm sure you can do the math).

It's like thin blotting paper, surface texture for prep is infinitely better than CSM. In fact I'm now using it as final layer even on hidden internal repairs for that reason. I just put a larger piece than the repair over top of any CSM. Its easy to tear off any unwetted tissue from around the sides after the resin has gone off.

Regards

Gerry

[cabc26b]

Bill,

I have used the .3 oz tissue with west epoxy system resin. I the drape returns once you apply the resin so no worries on compound curves. like Gerry mentioned it really is nice to work with -

George

[gerrym]

Bill, 30g/m2 works out about .9 oz/sq yard.

Even 30g/m2 is very fine. Sometimes, Ive used 2 layers.

Regards

Gerry

[gerrym]

George, you mention using West System to wet out the tissue. Do you have any sanding problems with this. I found that it was more "floury" if that's the right word compared to using polyester. Of course the West System epoxy will give a stronger more water resistant repair. Maybe I did'nt wash off the amine blush after the epoxy had cured. Time for another go with that system?

Regards

Gerry

[Gordon Sauer]

Tissue is cloth, very strong and hence why it can be so thin. Matt has all the fibers running every which way and builds depth. The various weights can be purchased at hobby shops since used for repairing RC planes and things. The book by Practical Classics called "on Lotus including Elan resoration" has chapters by Miles Wilkins showing his technique. His original book cautions against fibers being exposed on the surface and later showing through the paint. I regelcoated any areas that got down to glass fibers. I don't like using epoxy with polyester, potential incompatibility isssues. Gordon Sauer

[gerrym]

Gordon, beg to differ.

The kind of tissue most of us are referring to is indeed very fine CSM (chopped strand mat), made of very fine individual strands indeed. It is most definitely not woven (no weft and warp). As such it has little strength.

See description from East Coast Fibreglass Supplies Website

1Mtr Surface Tissue ?1.25

A very fine mat, ideal for making intricate shapes and also gives a better finish on completed laminates when used on last layer.
Can also be useful as a barrier between the gelcoated surface and the course strands of the matting to prevent print through.
Approximatly 30g per sq mt.
Fast wet out. Compatible with most resins inc. PE, VE , Epoxy, Phenolic

You are right to say that any woven cloth will inevitably "print through", no matter how fine.

Regards

Gerry

[Gordon Sauer]

Interesting--when you look at the Wilkins pictures of its use definitely looks like cloth with its perfect tiny square pattern but you're right, further reading says it's a mat--The very thin stuff I used throughtout was cloth bought at hobby stores--have never seen chopped stuff in US that thin--boat, hobby or whatever. Gordon Sauer

[cabc26b]

Gordon, US has plenty of sources - I have procured "tissue" from the "composite store" I use epoxy because it cross links and the tensile strength is something on the order of 4 times what vinalester or polyester will get you. Beyond this polyester absorbs water which is a real pain down the road . If you prep the surface epoxy will bond much better to the glass than polyester.

Gerry , i use west 105 resin with the 205 hardner, I have not noticed it to be any more flowery and it sands fine in combination with tissue. The west pump system is also nice for making small batches when you are in imperfection rectification mode on a shell ( which for me is also a multi step phase) . I don't do this enough to mes with the more "pure" aircraft grade epoxies .

George

[bill308]

Thanks for all the feedback.

I've used West System Epoxy before and it's really nice stuff. However, when working on polyester based auto bodies and boats, I am really hesitant to use it unless there is an overwhelming reason to do so like long periods of immersion in water or if there is a stength or stiffness requirement that can't be met with a polyester based product, like if the end profile is such that one can't add sufficient thickness to get the needed properties.

The way that I understand problem with epoxy based repairs over polyester is that once committed to epoxy one can not then go back and use polyester. Epoxy works over polyester but polyester does not work over epoxy. An interesting case in point was an S2 with a fractured windshield frame where it met the body. This section was of minimum cross section and could not deviate from it's original shape. After properly preparing the damaged area, the repair was made with carbon fiber and epoxy to restore the original strength.

Bill

[Gordon Sauer]

See, I figure the point of overcoming stress cracks is to strengthen what was originally too weak--like door handle/hinge attachment points, headlight pivots, etc so it made sense to use a really fine cloth--even more amazed that you'd go back with such fine mat with such little strength but I guess if it works and you're right, everybody refers to retissuing. I hope it will hold up since I thought I was retissuing and technically didn't although logically seems cloth might hold up better. And yea, since I went back to finishing gel coat on any repairs before any primers (used K36 all the way) then I didn't want to mess with epoxy since gelcoat is polyester--except I did use it in the front wheel wells (where gelcoating was not done) since my nose section had delaminated some and I wanted a bunch of strength. Gordon Sauer

[silkworm0818]

It's been reported that some quality restoration shops cover the body skin with a fine fiberglass matt, sometimes referred to as tissue. I like the idea of this method as it helps tie the surface together, especially after repairs, with a uniform surface and that may inhibit the return of minor stress cracks that go undetected. It also suggests the possibility of effectively dealing with pin holes and other defects uncovered by extensive grinding, that one may not want to use filler on. I also don't want to change the thickness of the glass body or ruin character lines that I've worked hard to establish, hence it must be pretty thin and able to conform to compound curves.

In the US, matt is identified by its weight per square yard where 1.0 oz matt literally weights about 1.0 oz per square yard. In Europe I believe they refer to it in gms per meter but I could be wrong.

At home I have 0.3, 0.5, and 1.0 oz weights. I've noticed that the really light weight tissue is relatively stiff for its weight, presumably to enable handling with out falling apart. I found this stiffness can cause issues when trying to make it conform to compound curves.

What weight matt is used to tissue a body?

Bill

[silkworm0818]

Hi,Bill,
Please try FRP surfacing tissue,30g/m2(2 layers).If you need it is too thin,please check 50g/m2 ones.
If you are still can't ...,please visit our web to get more information about fiberglass tissue.www.fiberglass-mat.com

I am producer.