Making Moulds

 

The process

On this page I have 3 examples of the process of making the fibreglass moulds, The first thing I'll say is make sure you have & USE the proper protective equipment & clothing when using fibreglass, or you will scratch yourself red raw & I'm not sure it would be all that good for your lungs either, so be wise.

Once I had let the rocks & soil settle in for a week or so, with a bit of watering to help. I set about thinking of a way to make the moulds match the rock exactly so when the plants covered the edges they should in effect disappear.

 

Placing the cursor over will change to alternate pictures.

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Wire frame completed.

Alternate picture, shows after the first layer of glass.

Step 1

I dragged out a whole pile of old plastic shopping bags & a few other large pieces of plastic that I had squirreled away thinking one day they could be useful. With these I started to line the areas where the moulds were to be made, I made sure that there was plenty of extra plastic on the sides so as to stop any runoff of excess resin, also the bags were laid from bottom to top so any overlaps were the same as roofing tiles hence keeping any flowing resin where it is meant to be.

First layer set, ready for second layer.

Alternate picture, shows completed tray ready to be installed.

Step 2

Now I had to come up with a way of giving the mould shape at the same time defining the edges as well as giving the fibreglass something to grip to, this also had to give the wet fibreglass some rigidity until it went off. To achieve this I used very fine bird wire, holes about the size of your finger. This was formed into the desired shape by pushing it into the shape of the rocks & corners, I wanted to get it as close to the shape of the rocks as possible, I allowed about 75 - 100mm for the side of the moulds. This was so I could place rocks in the trays to allow me to make small rapids & swirl pools.

Mould shape formed in soil.

Alternate picture, plastic & wire form work done.

 

Step 3

Now it was time for the fibreglass cloth, I used "150 gram chopped strand matting" with normal polyester resin . It is very important that you use a respirator while tearing up fibreglass cloth, I try & be as careful as possible where it comes to handling fibreglass in all it's stages, if you ever rip up fibreglass cloth in bright sunlight you will see why you should never handle it without a respirator & why you should handle it as gently as possible. In bright sunlight you can actually see the thousands of tiny fibre's floating in the air. Anyway I tore up enough cloth to cover the wire form work twice & allowed at least 1 - 2 cm's over the edges.

 

Fibreglass laid out ready.

Alternate picture, first layer finished ready to fit.

Step 4

Now comes the messy part I mixed up small amounts of resin first, about 250ml until I found out how far it went & how long it lasted, you only want to mix up as much as you can use in about 15 minutes. Because of the shape the only way to get the resin on is with a paint brush. It is painted on much the same as paint but with more of a dabbing motion, after a few seconds the glass starts soak up the resin & begins to go translucent the fibres seem to disappear. You have to work from top edges down working the resin in so all the air is worked out being careful not to push holes in the cloth once it is wet, you will start to see the areas where there is not enough resin as they will appear a frosty white. You have to try & get it all out as you go as once it starts to go off (harden) it is to late. It is better to apply a bit more resin than needed than not enough, it is easy to tell when you have enough as it will go translucent with no frostiness. Once the fibreglass had gone off (gone hard) I carefully removed it from the rocks, the first thing was to remove the backing plastic from the mould, there were a few small spots where the resin had not completely flowed through the cloth, I made up another lot of resin & touched those spots up as well as sealing the back of the mould.

Preformed shaped in soil.

Alternate picture, fibreglass cloth ready for first coat of resin.

Step 5

When the back was all finished I turned it over & laid the second layer, is placed on the same as the first only this time you paint a liberal coating of resin on the mould & them place the fiberglass cloth down & apply more resin to the cloth, it is important at this stage to work ALL air out as you go so there is no frostiness at all due to air still in the cloth.

It is important to handle any newly made fibreglass pieces with heavy leather gloves as there can be very small extremely sharp crystal clear pieces of glass protruding from them & believe me they are hard to find in skin. A good stiff brush can be good for removing them. A small grinder is used to clean the edges up & cut any excess off. Most important to use a respirator & goggles when cutting fibreglass with a grinder.

Finished tray in place.

 

Alternate picture, my dog giving his approval.

Step 6

Once the second layer is dry & cleaned up I coloured it with & brown coloured flow coat & used small gravel to give the effect, this has to be done very quickly, the gravel is thrown onto the wet flowcoat & sticks as it dries. I used this method for my first one. I used a different method with my others which enables me to colour it exactly the same as the soil where it is to be used I wont divulge that process here sorry. I may if you email & ask me & that is a MAYBE .

:-)