It is strange that the residue is appearing now.  That would imply there is some reaction still going on now (or recently) many days after the initial cure. -  which would point to something leeching off the silicone surface.

So as i read it , you did NOT use the spray release this time?  If thats the case  it points towards solvents from the release coat, although if you have left it more than an hour  between coating and pouring silicone then they should all be gone.  Unless perhaps some of the solvents had soaked slightly into the  Pattern Coat surface and it outgassed slightly during the silicone cure.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I dont mean completely uncured, I mean somewhat 'green'. Its a similar situation to demoulding epoxy too early. It can feel rock hard, it's even stiff and solid and not sticky at all - but if you demould epoxy too early, it will grip the mould like all hell, and cam destroy moulds. Very common with 'slow' hardeners where people dont give it as long as it actually needs, so even after 24 hours it is still not properly cured and hasnt reached the appropriate barcol hardness to release.

Silicones are similar. If you try to demould too early, theres a stage of the cure where it behaves as if it is totally bonded - even though it isnt.

Wow Turk, are these the quad headlamps for the T4? I remember the thread in the T4 forum from years ago, is it still running?

Thanks

Wow Turk 

 Busy Busy Busy good stuff!, I hope to retire to france myself one day!!

Sparky

Hi guys,

Thought I would post an update on the Quad Headlight Project, but more importantly how I got on with my replacement CS25 Silicone rubber  ( thanks Warren ). I think it's only fair that I should share my results using CS25 silicone rubber as everyone has been so helpful, and are probably wanting to know themselves how things turned out. I'm no expert guys, many of you would probably have worked that one out yourselves!

So my recommendation would be ( and that's purely my opinion ), what I concluded was the mould release agent I used wasn't compatible with the silicone. Probably totally wrong!
So, on this attempt I used the 'Mann' Ease Release 200 mould release agent that comes in aerosol can.

 This was what I was left with after my disastrous first attempt,  the silicone mould was useless and my plug was damaged, the other one was even worst! >>


First thing I had to do was to repair my plugs, as they're basically layer upon layer of Pattern-Coat Primer resin, I had to sand-back most of the previous layers, and then begin to re-apply really thick layers of PcP in the broken areas ( a bit like using Polyester filler ) >>


Because I the headlight design,  these will actually be for the headlight covers I intend to use,  there's a line ( that I call the 'swagline' )  all the way round the plug,  it kind of makes working with the plug awkward,  simple things like sanding become quite awkward,  but it's needed for making the part structurally sound and adds definition to the shape.  So in almost every step of the process I have to add blue painters tape to either protect the swagline or give it form  >>


Then the sanding begins ...................  If you hate sanding stuff,  mould making isn't for you!  >>


Lots more sanding later .....................  the 'swagline' is well established,  and it's just a case of working the plug till you regain the initial shape back  >>


A few more days of sanding,  all the while checking your dimensions,  you're almost back to where your were the previous month  >>


Now it's just a case of working through the sandpapers  >>


After the 1200 grit wet & dry things are beginning to look up.  It never ceases to amaze me just how good you can get the Pattern-Coat Primer to look.  It's like a glass-like finish it's that smooth.  And that's without using the 'Pattern-Coat High-Gloss' finish >>


Then it's onto the polishing stage,  then a few coats of wax.  I got the things so buffed up that I could actually read the wattage of the over-head light reflected in the plugs!  >>


Now the plugs are fully repaired,  buffed up to a high sheen it's time to install them into my mould set-up boxes.  As I need to reduce the hight of the plugs by 30mm ( that will become my 'tooling plugs' for vacuum forming my parts ),  I simply glued the batons in place and filled the voids with 'NewPlast' plasticine  >>


As the bottom of my mould set-up box will become the top on my actual completed silicone mould,  there's no reason to make a pigs ear of it.  The edges must be crisp and sharp >>


I'm not going to go through the entire CS25 silicone preparation and pour,  as that's already been covered  on the first page,  as I've already mentioned, the only thing that I did differently was to use the 'Mann' aerosol release agent.  De-moulding time - Already things didn't look good!!!  the sides of the mould box were well stuck ..............  it took quite a lot of persuading to release the sides,  no damaged was caused to either the silicone mould or the set-up boxes themselves ( I will need those again in the next stage ) >>


In the end,  everything worked-out just fine    well pleased with that >>


The quality of the silicone finish is superb and the definition is bang on.  And as intended ( hoped ) the swagline is nice crisp and sharp >>


The next stage will be to cast 'Vac-Cast Epoxy Resin' into these.  But a solid block of vac-cast resin isn't what I want or need.  For a proper vacuum forming tooloing plug,  the tooling plugs have to be hollow.  I'm hoping to use plasticine,  about 20mm thick ( rolled-out with a pin-roller ) to 'line' the bottom of this silicone mould.

Does anybody see any issues with that method?
I'll be using cling-film as a barrier so the plasticine doesn't stick to the silicone.

My other question,  and really my reason for posting this article,  PLASTICINE ..................  can I put plasticine in a microwave oven to soften it?  I've made a 'heat-box' to soften the plasticine, as I need it to be malleable so I call role it into flat slabs.,  but it takes all day just to soften it just a little!  Microwave method any good?

Anybody tried this method?  I'd like to hear from you if you've tried this.


And just to finish off ...................  The only issue I had ( the silicone sticking to the sides of the mould set-up box ),  was due to the fact that the 'Melamine' wasn't actually Melamine at all,  but just a cheap finish to make it look like Melamine!  When I looked closely at it and picked at it with my finger nail,  I realised it was a type of compressed cardboard made to look like Melamine!  The junk they make now days,  nothing' real anymore!



TURK
T4 Concepts