Here we have a view of half the tub mould. It’s been flatted, sanded and polished. It’s not a fantastic mirror shine, but it really is quite shiny. in the left hand picture you can see some black gel-coat where I’ve had to make a repair or two. You can also see some white where I’ve flatted back to the undercoat. Not a problem here.

I’ve learned loads from this half, and now when I get time I’ll do the other half. Ideally finished this week. I think there were 5 hours of work in each half to get to this finish. Flatting was done with a P800 paper attached to a dual action orbital sander. Once flatted (and I’ve got other pictures showing how it looks so you can see if you’re finished the flatting process) I then ran over it with a P1200 to start the polishing. Then with a industrial polishing thing, a P1500 cutting polish, P2000 cutting polish, and then high-gloss and swirl removing polish.

Next steps are to apply mould cleaner and mould sealer. Then 5 coats of release compound. Then … I can actually lay up and pull a part.

Here’s the tub finally released before it was lifted out. It took quite an effort to release it, with multiple use of wedges, squirting water, and at one point, the 2lb percussive force transduction instrument to knock out the internal bracing in the transmission tunnel out. There was a large amount of plasticine in one part when I was filling in an undercut. At one point I was lying on the ground and trying to push the mould up and out with my feet. There was also some action with the trolley-jack as well to free it up.

         Here it is out of the tub. It hasn’t been trimmed yet and it didn’t really change colour as I could see after I post-cured it, but it feels as solid as a rock. It’s pretty heavy as well, and I can’t move it around on my own. You can see where you sit, and it’s not symmetrical – it was not designed to be – the Fury has a bend in the transmission tunnel to allow the engine to be offset to the passenger side a little bit to set the weight balance more evenly 50/50 down the centre-line.

Now we’re looking down it as you sit in it. It is worth noting that the footwells are only in the mould to make it a closed container. I will lay a couple of layers of e-glass in there just to keep the part dimensionally stable, but they will be cut out of the final part. This then gives access to your feet for the CF footwell and steel footwell I have already made. I will need to cast up some jointing strips between the tub and the footwells, just to make extra sure everything passes force to everything else. This process will be a really easy moulding process – just put some gel-coat down,  and then slap some shredded glass putty (like isopon p40)  behind it. I may use glass and epoxy paste though, to ensure better mould compatabity. If I use this, I will need to bake it for a while to be sure all the styrene is out, else I won’t get a good epoxy part.

Here is the mould now fully out of the car. It’s a positive mould (if you hadn’t guessed) and needs trimming and polishing. There are one or two bubbles behind the coupling coat where the gel-coat will come off, so these need either digging out, or if there’s a small break, in a larger bubble, I can inject repair gel-coat in behind it which will bridge the gap and make a solid plug with the minimum of sanding and polishing. Most of the tub gel-coat is really solid though.

Here it is from the other side. The white stuff you can see all over the place is the plasticine I used to form the inner radii. I will scrape it off, and then clean it off (hopefully acetone will shift it), then it’s polish, polish, polish.

I have a machine polisher so it’s actually not much of a chore, and there are two coats of gel down, so if I start seeing white behind the gray, I know I’ve gone as far as I dare.

Here we have an inner radius with the plasticine scraped off. There’s a small ridge there (looks a lot worse in the photo) which will sand off with a bit of wet-and-dry. I will start with a fine grade (say 800) and see how that does, before finishing off with 1200, then 1500, then polish, then wax.

Finally, here’s the money shot down the tunnel.

The inner radius transferred brilliantly from the part, but it will need some rubbing to bring up to a good polish. I did form the shape with body-filler and then waxed it, so it was always going to be an OK finish. Because I sprayed PVA release over the poly board (which is meant to have a good inherent release), I didn’t get the full shine from it, but there is a bit of a shine there already. It will be trivial to polish up.

Look at the bloody mess the demoulding process made. This was after I gave the garage a bit of a tidy and did a tip run. Sigh. Guess I’ve got to do it all again.

right then. time to turn this huge amount of gelcoat into a mould. First stage is to get down the first thin coupling coat.

When trying to overspray the PVA with a very dilute solution, we find it fish-eyes and no amount of brush-work puts it right. 

Peel it off, wash it off, and start again

 I could have gone for leaving the matte finish from the original PVA I laid down but then that would have negated all the benefits of using the really nice shiny plastic. Only option is to clean it all off and start again. If I was to go with a matte finish, it would mean lots of time spent polishing parts rather than letting the part material do the work for me.

So, here’s the tub, with a dust cover over the top. Great, thinks I – all is now ready for spraying. To be sure it’s ready, I have vacuumed it and cleaned it with a micro-pore cloth and panel-wipe.

Now, I’ve started spraying the PVA. There’s still lots to do though – I want a nice thick heavy coat on. It’s a shiny finish PVA, but it’s not coming up as shiny as the original back on the poly board.

So, my potential problem is that I have left it a little tacky when I put the dust cover back on. It will, or it won’t stick. It is release film so I stand a chance. worst case is I get a sponge brush from East Coast Fibreglass, and they reckon you can get a good finish from that.

Needless to say, I can resurrect some of the finish imperfections here in the final part. The final part will have an outer layer of clear gel-coat which will take a bit of flatting and polishing if I need it to.