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Now having had one stick up using just wax and having destroyed my dome plug, I did some more research this time and decided that I'd use lots of PVA (not the glue but Poly-Vinyl-Alcohol release agent!) on top of wax.

As I said on my previous page, it’s best to leave your mould outside until it stops smelling.

Step 1: Prep your mould

  • 1) Wait for any resin smell to go from the mould - seriously be patient!
  • 2) Clean and wax the mould. Wax on, wait 2 minutes, then buff a little, then leave for 1 hour then repeat 5 - 8 times on a new mould; 1 or 2 on an old one.
  • 3) Spay a fine mist of PVA (Poly Vinyl Alcohol) release agent. Wait an half an hour then apply again a few times until it's blue like the picture. (trust me ignore everyone else). It has to be fine and not two thick else it will fish eye on the wax and or run. Hold the gun about 45cm away and apply many coats rather than one thick one.
  • Step 2: Coating the dome - (Option 1) Gelcoat

    Now when I made my first dome and wrote this I initially used white gelcoat to get a thick cover. Gelcoat is really just thick resin that doesn't run so is useful for sticking to sides, like a boat hull for instance. It also gives a more durable finish and can be coloured. It is however not essential.

  • 4) Mix up polyester gel coat; now if it's just too thick it may pull off the PVA, so mix in a little resin to thin the gel coat. (was a gamble but worked perfect). The standard mix is about 2% MEKP
  • 5) Apply the gel coat with a cheap paint brush. About 350ml in case you are buying some was needed for a single thin coat.
  • 6) Hang around for 10 minutes and brush out any air bubbles and runs. Once it starts to get thick, go get a hard earned cuppa if you're English.
  • 7) Leave it for about 30 minutes to an hour depending on the temperature where you are. Wait until is slightly tacky but doesn't stick to your skin. Don't leave it more than perhaps 2-4 hours.
  • Now go to step 3

    Step 2: Coating the dome - (Option 2) Cold Cast Aluminium

    I came up with the idea of trying to make an aluminium dome from saturated cold cast resin and after a few experiments have managed to acheive a pretty impressive result. The only draw-backs are that this method is more expensive, it't trickier because of runs etc and the dust is dangerous.

  • 4) Tip about 350ml (a coke can size) full or aluminium powder into a larger tub and mix in some polyester resin to form a very thick paste that is just slightly runnier than car body filler. Add the 2% MEKP and mix that in. DO NOT BREATH IN THE POWDER!!
  • 5) Apply the mix with a cheap paint brush. It is very gritty feeling so be careful not to scratch the PVA, it will also run a bit so start at the edges, not the center.
  • 6) No time for tea with this option; Hang around and brush out any air bubbles and runs. Keep working it until it eventually becomes think and stable. Patch up any holes with another coat if needs be. It is difficult to get full coverage in one coat and you need a good coat for sanding later.
  • 7) Leave it for about 30 minutes to an hour depending on the temperature where you are. Wait until is slightly tacky but doesn't stick to your skin. Don't leave it more than perhaps 2-4 hours.
  • Step 3: Laying up the fibreglass

  • 8) After about 20 - 30 minutes check and see if it's finger tacky It must be tacky to get a good bond and too soft that the matting goes though it.
  • 9) Now apply a quick coat of resin and then a layer of matting. (note the shape of the matting pieces) Use a brush to dab out any bubbles with more resin. The resin will soften the matting.
  • 10) Wet out the currently applied matting with plenty of resin and apply another lay of matting. Then resin that. I applied two layers and a third strip about 75mm just around the bottom of the dome like a collar as this area will have a grove cut in it.
  • 11) Have a quick dab over, working it all in nice then sit back and panic about how your are going to get it out!
  • Leave it for 24 hours........, time never goes slow!

    Step 4: Unleash the dome!

    Okay, so do what you need to do but carefully. Now you will appreciate why two lays for the mould was better than four (as you can just about distort it) and why I said use both PVA and wax!. I rolled on mine, wedgied it and squashed it...the odd creak but no release so I tried hot water / a hydo-release!.

    I levered open a gap and poured in hot water around the rim. Some of it soaks in so pour some more and more in until you hear creaking. Eventually it will take on more water and then..... out pops a new born dome covered in blue water like a big baby's head!!

    Look at the bottom picture and you will see where I've started to polish the dome. You can see the aluminium starting toe gleam through!. Perfect; looks like a real aluminium dome up close.

    Up next...Dome: cutting and painting the dome

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