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Step 3: Preparing the Patches

How many layers of fiberglass cloth you use depends on how thick your fiberglass shell is. Since I was trying to repair a 1/8" wall, I thought 3 layers of fiberglass material would be appropriate. 

A sailor friend of mine informed me that I would need to glass in a large patch first, and sequentially step down to a patch the size of the hole. I used kid scissors that I didn't particularly care about to cut the patches.

The largest patch extended a little past the outlined perimeter, with the next two patches cut sequentially smaller.

<p>If the surface is vertical, and your patch large so its weight would allow it slip down, I use two sided tape to stick the DRY cloth onto the hole, then use a paint brush to paint the resin onto the cloth.</p><p>And talking about hulls, anyone have thoughts on applying gelcoat so it is a perfect smooth surface?</p>
<p>If you want a properly strong and flexible finish, try this: since glass fibre mat is made up individual fibres thinner than human hair which are bonded together to create strands, the correct method is to stipple the mat with resin &amp; a brush until the strands are broken down into the fibres and each fibre is consequently surrounded by resin. The strength of GRP comes from the fibres not the resin, and so long as the fibres are surrounded by resin you will achieve the lay-up. Consolidating the area with a metal roller will make the whole thing far stronger and also bring excess resin to the surface. (Don't forget to clean equipment in acetone for next time!)</p>
<p>When wetting your patches, do it on a sheet of polyethylene (US spelling) sheet of some sort, such as the corrugated plastic campaign signs that are everywhere here. Don't do it in your hand. I would prepare a series of circular patches but I'd place the smallest first, and after painting the area to be patched with the resin. Smallest-first gives you flat, parallel layers.</p><p>Also, the warnings about curing may be overdone. Once catalyzed, resin is gonna cure. Slow or quick, but it'll cure. Letting sun hit it is also a catalyst. The fumes inhibit curing, and are heavier than air so if you are working in a bowl shaped place, you need a breeze to move those gases out.</p>
<p>Hi, when laminating a hole and where you have access to the outside of the repair, you should use a temporary backing to which the glassfibre will not bond. Eg a bit of polyprop plastic covered with polythene or cling film or a specialist non-stick material called peel ply. If doing this, you can lay some gel coat (to give a good finish to the outside of the repair), before adding the fibreglass layers. Hope that makes sense.</p>
Am a fiberglass moulder (lamination) I want a job in London
<p>Thanks for the great information!</p>
<p>I'll have to give this a shot at work. We' have some minor cracks and dents in the glass that could use some fixing up. If the problems keep up, we'll have to get a professional eventually. Otherwise, this doesn't sound like that bad of an idea to get fixed. I'll pass it to my superior and hopefully he'll approve this project.</p><p> http://www.ejfiberglass.com/Services/ </p>
<p>Thanks for the clear instructions, I repaired a large pot in a fountain after reading this.</p>
Edit: &quot;BONDO&quot;<br><br>(darned autocorrect)
Why didn't you use Bonding as the filler?
Good! <br>Went to my Blog, and see there, also, 2 Posts down, about Sandables: <br>http://faz-voce-mesmo.blogspot.pt/2013/01/reparar-fibra-de-vidro-rasperry-pi-e.html
Very useful info, Audrey, thanks for sharing it.
Thanks!

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