Cheers tom21. Yeah learning this way has it’s ups and downs, but you can’t just sit back reading books - eventually you just gotta get in and do it! I just try to remember to take a photo at each major step - usually not hard for me to remember because each of those points is like a milestone for me. Haha.
it has its issues as you almost always get a thin spot in the filler and have to gouge it out and add more filler.
:laugh:
That is exactly what I discovered making the change to the front fender! But no biggie, easy fix. Sure is better than messing around with clay. I think the only place I would use clay again is if I either worked it more to get a really good, smooth shape (and then coated it with PVC or something so it didn’t stick to the glass and stop it from fully curing) or if I was doing a very large part (no point in using lots of foam when you can just build up the shape with bricks & clay).
Good tip on avoiding the pinholes. I actually have some old gelcoat here, should have used that probably… but then I wasn’t sure if you can use body filler on top of that? Since I had planned to modify the panels. Part of the problem is that I rushed those parts, they’re not really so much pinholes as places where I didn’t wet out the glass properly. 
Well I made some progress since the last post, so here it is:
First up the good news, the remodelled fender plug is all complete!
Fender Plug - Complete by mugget, on Flickr
I have a couple of parts that may need small areas filled once the primer is blocked down, but better to do it that way rather than trying to put filler on top of filler… I seem to just keep using more and more filler and sanding more away if I do that.
I got my LED lights up in the spray booth type area I made, much better for painting in. So I sprayed the basecoat and clear last weekend while it was raining! No problems! I think the problems only come when you have a situation that can cause condensation, like if it was summer with high humidity. But since it’s winter, I didn’t think that condensation could form by blowing cold air onto a cold job, and it didn’t.
I was really happy with how I managed to spray the base, no runs, would have just preferred to spray one more coat but I ran out of paint by the time I’d done all the gun setup - all that setup is worth it though!
The clear… well that’s another story. And that’s the most important bit. Basically it was starting to get dark (even though I added light to the spray area, it’s not so much that I can work in dark) so I was rushing a bit, and didn’t get the gun setup right for the clear. It was spray wayyy too heavy, got some massive runs, clear dripping down onto the floor. The clear seems to spray on really heavy like the high-build primer, just gotta get the setup right next time and I’m sure I can do it. But even with that snafu it was salvaged.
Painted Test Part by mugget, on Flickr
That photo actually makes it look much better than it was in the real. I only cut & polished some sections. Ripped into it all with a 360 wet sand to try and level out the massively oversprayed clear. I wouldn’t do that on any actual parts because it’s too hard to get the sanding marks out. Well, I’d hope not to overspray anything again, but if I did I would just spend the extra time with 800 or 1000 grit before going to 1500 and 2000.
I did manage one tiny area without any runs or orange peel, and hot damn if it wasn’t super-smooth and super-glossy off the gun!! Now I know why everyone gets hyped when they get a job that is good off the gun and doesn’t need any polishing!
Next up was to put down the gel coat.
Gel Coat Test by mugget, on Flickr
Added a smidge of black pigment to make it easier to spot air bubbles.
I used a varnish brush for this (low bristle density and uneven edge), I will use a better brush next time so I can get the surface more even with less low spots. Even though it didn’t look like it caused any problems due to the gel coat being too thin - better to be safe than sorry.
Test Layup by mugget, on Flickr
Only added a single layer of 450g CSM since it’s just a throwaway test piece. Cut up some CSM and put that in the recessed holes, wetting it out with resin. Seems to be a much better way than filling the holes with resin + talc mix, then just glassing over the top.
Annnnd here is what it looked like when I demoulded this arvo:
Test part demoulded by mugget, on Flickr
I think this may have happened for a few reasons. Firstly I didn’t polish the entire piece - the areas where the paint lifted weren’t polished. So I have a theory that even though it was waxed, the resin had too much mechanical grip there. What do you think?
2nd - The gelcoat went over the edges of the part in some places, so I took a knife and started cutting/chipping it off. When I went to put a paddle pop stick in to separate the part, it’s like it just went in straight under the paint (well, between the primer and basecoat).
Then again, I wouldn’t have expected the paint to just lift away from the primer like that? Maybe that is why most car guys say to leave 2k paint for 2-3 months before waxing or polishing etc.? So it can reach full cure? I think I’ll just bring in a heater to the spray area after I spray the next base & clear, because I can’t let this sit around for months, gotta move on!
3rd - the upper left triangle section was coated with PVA release, and came off easy as anything. The other bit that kept most of it’s paint was a polished section. So on the actual plugs I will make sure to polish them all as glossy as they will go. Actually I think I will go back and try machine buffing the good paint area, and try another small test. Gotta know for sure if it’s going to release okay with just wax or not.
The other thing could be that I took off too much clear when I was trying to block it down, those areas with paint missing were the most overcoated with runs and orange peel on the part. If I do have to sand the plugs down that much, I think I will give it another coat or two of clear so I dont’ risk it.
At least I know there was no chemical reaction between the gelcoat and paint. I peeled off some bits of paint and did the rest with a metal scraper and the paint just came off the test mould. Good to know that the gelcoat is pretty tough as well!
That’s all for now!
Update: I just got back from my local composites shop, picked up some new mould release wax because I thought the old stuff I had may have been causing problems, and I was nearly out anyway.
Well, turns out that I just haven’t been applying the wax 100% correctly. My suspicion was right - that if the plug surface isn’t polished smooth it can be harder to release. So that would explain why the section I polished released better than the rest. But the wax should also be buffed to a high gloss - you basically shouldn’t see any buildup of flat looking wax, the wax is there, but you should just see your mould/plug surface. Also it was suggested to me that I apply the wax using 4 different cloths. One that you dip into the wax and apply to the part, then the other 3 you use to buff up the wax, rotating to the final cloth which should be staying virtually clean and wax-free. Then when your 1st waxing cloth is too waxy, just rotate them and keep going like that, keeping your final cloth clean for the final buff. 6-8 coats should be good for a new part, but if unsure you can always do a couple more coats. You can’t really put too much on, and better to be safe than sorry, because you don’t get any 2nd chances.
Now that I know that, I’m confident that I can get a good release and high gloss finish when I make the final moulds. Now I’ve just gotta start all the paint prep on the plugs that are finished, get this moving right along…
