Hi I have the manufacturers name moulded into my campervan's pop-top fibreglass roof but I would like to replace it with the campervan's name PHILEAS.



I will just sand it off so will have to make it slightly bigger to cover the sanding I have purchased chrome letters that you put on the boot of cars, in order to make a mold from but have no idea how to do it or products to use. HELP!!



Here are my letters I bought





The original is on a type of plinth aswell any pointers gratefully received.

Hi,

Interesting little project, seems like an ideal candidate for a silicone mould and casting resin.

First job would be to cut a piece of material (Plastic MDF metal... anything with a smooth surface) to the size and shape of the base plate, then glue your new lettering onto this to create a pattern.

You will then need to mount the patten into a water tight box that is a little bigger than the part, this box has to contain the silicone when it's poured waxed MDF or wood is fine for this as long as to joints are sealed.

You are now ready to make the mould, simply mix a batch of silicone that will fill the box, covering the pattern. carefully pour this over the pattern and leave to cure.

After curing the silicone can be removed from the box and pattern, this should remove really easily even though no release agent has been used.

Making the part from this would be a really quick process, just mix up a small batch of fast cast resin and pour it into the silicone mould (again no release agent required) this will be ready to release within an hour!

To finish the part up you would just need to sand the back of the plinth flat with a sanding block (as this was the open end of the mould and will have the od ripple), to fit it I would spray paint it to colour match, then simply grind down the original one and bond this in place.

Everything you would need to cast this part comes in a handy kit found here There are no seriously harmful chemicals or smells involved so it's something you could probably get away with doing on the kitchen table!

Paul Statham
Easy Composites / Carbon Mods - Technical

I did look at the silicone mould and casting resin, so i'm glad I was on the right track.

I take it the part will come out opaque, as you say I'll need to paint it, is there a white pigment I could mix in with the resin, or is this not recommended.

Thanks for the "how to" I'm feeling very confident now.

Yes, you can add pigment of any colour to our FastCast PU casting resin. Make sure you choose pigments designed for polyurethane (i.e. don't use pigments designed for polyester resin or for epoxy resin). We have a limited range at the moment (please call us) but we'll soon have a full range of pigments for PU, EP and PE.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Well finally got round to using the silicone mould and casting resin what a great method worked a treat.

I stuck my letters onto a piece of perspex



I went to Tesco's to find something long and thin so I wouldn't use too much silicone, unfortunately the plastic boxes in the kit didn't fit my particular part but will use them for something else.  Cutlery tray won the day and there wasn't a barcode on it so I got it for 1p.


Silicone mixed and poured in.


This is the silicone mould removed from tray and original part.


I then mixed up my casting resin and poured it into the mould


The resin left in the pot gets really hot.  I waited until the stuff in the pot cooled down and was cured before attemtping to remove resin part.  By the way really easy to remove part from silicone.


Really happy with results, a few questions can you just spray paint the part with primer and paint or do you use a plastic primer first and will the part need sanded before paint?  What should I use to bond it to my GRP Pop-top?

Thanks for your help Matt and Paul it really is cool stuff.

That's some neat work,

I'm really pleased that it has worked out so well, with regards to painting I would recommend using a plastic primer first, polyurethane takes paint fairly well, make sure that you give the part a good de-greasing before application as the resin 'sweats' an oily residue a little during cure, you could post cure the part in the oven at 60 degrees C for an hour to fully cure of the resin before painting. after priming any automotive paint with be fine,

To bond the part to the roof moulding should be pretty straight forward, give both surfaces a de-grease and sand with course sand paper (around 60 grit) the bond the part in place using an epoxy adhesive like permabond or araldite.

I look forward to seeing it in place on the bus! 

Paul Statham
Easy Composites / Carbon Mods - Technical

Thanks for the painting advice, I gave it a light scuff with a sanding pad and used the primer and paint you suggested and it came out a treat.

Here is me sanding off the original




This is me checking it's flat to the roof


This is it stuck down with a 90 second epoxy glue from Araldite.


Thanks for all your help, I now have people wanting me to make one's with their name!

came out really good!

could be a good pocket money earner. perhaps do variations like different shape edge to the name board etc.

Good job well done