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[tigertiger]

I read on this forum that nappy liner tissue can be used as a substitute for glass fibre tissue. As glass tissue is used for a good finish, and not strength, this should be no problem.

I have also read somewhere (can't remember where) that kitchen cloth can be used internally to the hull as a substitute for glass cloth.
Are there any comments on this practice, the reason I ask is getting some supplies here in China is difficult for me.

If it is a suitable practice, what is a good cloth to use? A 'J Cloth'? A similar cloth without the holes?

[andrewh]

Tigertiger,

Difficult to be useful at a distance (ten years since I lived in China)

I use synthetic "felts" instead of glass tissue for surface finish and local strength.

I always keep suitable materail when I see it - basically any synthetic material in a "tissue" form.  Even cotton would be fine for a year or two, but would probably then lose strength.

My favourite source is garden shops where "horticultural fleece" is sold by the yard/metre - this is polyester tissue/felt  - soft and drapable.  Bonds with any and all known adhesives - I am having a love affair with acrylic varnish at the moment.  Used neat or filled with microbaloons as a filler/surfacer

Don't know what J cloths are made of  - while trying to find out I found
http://www.sauldharrison.com/shop_listProducts.asp?graphics=on&sID=200612273626699361&catID=24&parentName=Nonwoven%20-%20Industrial%20Wipes&hLevel=2&parentsParentName=Chicopee&parentsCatID=15
so they look to be suitable - go for it!

How about making a few trial panels?

ansrew

[gribeauval]

I read on this forum that nappy liner tissue can be used as a substitute for glass fibre tissue. As glass tissue is used for a good finish, and not strength, this should be no problem.

I have also read somewhere (can't remember where) that kitchen cloth can be used internally to the hull as a substitute for glass cloth.
Are there any comments on this practice, the reason I ask is getting some supplies here in China is difficult for me.

If it is a suitable practice, what is a good cloth to use? A 'J Cloth'? A similar cloth without the holes?

I have used these 'non woven' kitchen cloths (without the holes) for a long time, both inside and outside the hull. I stick them on with diluted pva and then if no other planking is to be done then sand down and seal with varnish/sanding sealer depending upon the type of paint to be used as the top coats. I find they give the finish and strength I need without the expense or the smells of grp (many brownie points with the wife as she has asthma!)
These pictures are from my 1/12th scale Oakley Class Lifeboat build.

[tigertiger]

Thanks for that Gribeauval, and Andrewh.

If you can use PVA, I wonder what the two pack (sealer and hardner) pond sealer would be like. There are two types here in China. One is flexible, the other semi-rigid. Both look like mud. Both can seal fabric by absorbing into it.

[Colin Bishop]

There is a one pack pond sealer over here called G4 which I have used on my full sized boat. Some deatails here: http://www.arghamvillage.co.uk/products/details/184.html

[andrewh]

TT

I believe, but I have been wrong before, that they are polyurethanes - should be very suitable.
If they are the warning/contents should say Harmful, "contains polyisocyanates" or something close

They should stick like something very sticky to a blanket

Which reminds me that Polyurethane varnish is another way to adhere the reinforcement to a hull - but when very thickly applied PU becomes hard and may get brittle - in thin layers it's flexible and moves with the hull

Gribeauval reminded me that using them between planking layers or between papie mache layers adds a LOT of toughness to a boat hull.  I believe that some double- and triple-planked full size hulls used canvas as an interlayer for this reason.

andrew

[gribeauval]

TT

I believe, but I have been wrong before, that they are polyurethanes - should be very suitable.
If they are the warning/contents should say Harmful, "contains polyisocyanates" or something close

They should stick like something very sticky to a blanket

Which reminds me that Polyurethane varnish is another way to adhere the reinforcement to a hull - but when very thickly applied PU becomes hard and may get brittle - in thin layers it's flexible and moves with the hull

Gribeauval reminded me that using them between planking layers or between papie mache layers adds a LOT of toughness to a boat hull.  I believe that some double- and triple-planked full size hulls used canvas as an interlayer for this reason.

andrew

All the old wooden lifeboats of the RNLI that were double diagonally planked were built with a calico interlayer for strength and flexibility as well as helping to keep out the water. That's how I built the 35' 6" Whitehills lifeboat.

[GaryM]

If J Cloths, Nappy Liners are used, would some of the more modern raincoats / Mac's be better?
I mean if you have a waterproof mac.  Cut it to size?  Would this be OK or would the adhesives melt / distort it? 
Just a thought.  (providing you have a disposable coat :))

Gary

[tigertiger]

If J Cloths, Nappy Liners are used, would some of the more modern raincoats / Mac's be better?
I mean if you have a waterproof mac.  Cut it to size?  Would this be OK or would the adhesives melt / distort it? 
Just a thought.  (providing you have a disposable coat :))

Gary

Last time I looked, proper raincoats (especially Macintosh) were well expensive. But Genuine macks are very thick indeed.
Some cheaper raincoats are made with a very close weave cotton (also the original SAS smock), when they get wet the fibres expand and water cannot get in, whey they dry the fibres shrink and the material breaths. This is also how the first Anoracks were made, these were the bright orange or green hill walking vartiety and predates the the quilted nylon types.

Just some useless information, now back to the topic. Before I hijack my own thread.

[John W E]

hi there TT

first of all, I think we need to understand a little basics about GRP (glass reinforced plastics) :

POLYESTER RESIN OR AN EPOXY RESIN

On their own they do not have any great strength values; if both materials were to be cast in an ingot form, and subjected to various tests - e.g. impact, crushing and bending tests they would fail miserably.   Admittedly the Epoxy Resin would fair slightly better than the Polyester.  We can assess from this that they are basically a 'bonding' or a 'cementing' agent.   This is why we have to add a second component - tissue mat, as used by the fibre glassing industry, is matting that is made up of millions of strands of glass rods which are the same thickness approx as the human hair.  These have been bonded together with a soluble agent in every direction on a flat plain.   The same can be said about the heavier grades of matting.   The two varients are the weight of the glass fibre strands.   However, the lengths of each strand are normally equal.   

So, the process now is when we add the resin to the matting, the resin disolves the bond in the matting and allowing the fibre glass strands to move freely in amongst the resin, being totally encased with resin.   This is where the strength comes from and also it is why air pockets/any impurities are avoided.   

WOVEN ROVEN GLASS MATERIAL

If we look at this material - this is a different system of matting.   This is where the glass fibre strands are of a longer length and they go for many thousand metres; these single strands are woven together to form a type of string which is then rewoven, as one would weave a blanket/cloth.   There is no soluble bonding agent to hold the fibres together, it relies solely on the weave.   So, in this case, when we add the resin to the weave, the strands do not break down.  They remain in the same weaved pattern - this material (when correctly applied) can be at least 3 times stronger than the chopped strand mat makeup.

Its downside though is that it is extremely difficult to work with being difficult to remove air bubbles from and get the resin to penetrate the fibres evenly.

You are asking for an alternative material; to add to the resin.   So I do hope you can see that the material you intend to use will influence the strength or durability of your lamination 

My advice to you is try to use a material where the fibres on the makeup will absorb the resin.  This in turn will increase the strength.    As a sidenote, some nylon materials, as in similar material to tights/stockings  :) slow down now......can be used with great success. 

Also, some of the nylons which have a 'flocked' side to its makeup can be used.   These flock types do absorb the resin.

You will find that on some materials which do not absorb resin properly, when you sand through and you hit the reinforcement material that you have opted to use, it will be soft - where the resin either side will be hard.  You will then get 'fluffy appearance' on the finished laminate, which is difficult to rectify.

Some thoughts for you......

aye
john e
bluebird