Releasing fibreglass from the mould, any tips? - Page 5 - 10-Tenths Motorsport Forum

Speedy1 · 17 Jul 2007, 20:05

Quote:

Originally Posted by dtype38

Good point, although I use Acetone which I get by the gallon from my local friendly fibreglass supplier cheaper than I can get cellulose thinners from my local paint place.

Oh, on the subject of cleaning things.... anyone got any magic potions or secret methods for removing the glue left when I peel my numbers/roundals/sponsor stickers etc off? I'm struggling to find anything that does it without damaging or softening my cellulose paint. So far the best I've found is to give it a wipe over with RainX then rub off with a rag soaked in Acetone. Very effective but also quite expensive!

The magic potion I use for sticker or tape removal is WD 40
a light oil in an aerosol can
take the remaining oil & residue off with isopropyl alcohol

**dtype38** · 17 Jul 2007, 21:41

Thanks Al and Speedy, I'll give those a try. Oh, and sorry for not paying attention Al, always was taking at the back of the class when I was supposed to be listening.

***Chris Y*** · 18 Jul 2007, 09:15

Jizer, or some other degreaser often works for removing adhesive residue. You have to give it a good old rub though!

trikesrule · 18 Jul 2007, 09:42

D Type I detail a lot of cars at my work. Petrol works real well at removing the glue residue. Give it 15 seconds to soften the glue then just wipe it away. No problem..........trikes

trikesrule · 18 Jul 2007, 09:50

Guys don't use thinner to prepare a surface for glassing. Ok to give the surface a wipe if your going to paint it after it's released - just don't use heaps or you will reactivate the resin especially if it's followed immediately by a bit of warmth. Al pva washs away with water. I peel as much away with my finger nail then rinse the rest away with the hose............trikes

Al Weyman · 18 Jul 2007, 19:13

Ok Trikes I will try that on the next one as I doubt this one will last long before my magnetic attraction to the kitty litter draws me in again!

**dtype38** · 19 Sep 2007, 15:03

Can I just come back to the general topic of tips for fibreglass and ask a question about how to finish a buck/master before making a fibreglass mould from it. Say I've just made a shape from wood and body filler, what sort of paint/finish is best to use to get it completely smooth. Should it be a gloss or mat finish and if the latter, what grade of wet/dry would you use to finish it?

StephenRae · 19 Sep 2007, 15:27

Quote:

Originally Posted by dtype38

Can I just come back to the general topic of tips for fibreglass and ask a question about how to finish a buck/master before making a fibreglass mould from it. Say I've just made a shape from wood and body filler, what sort of paint/finish is best to use to get it completely smooth. Should it be a gloss or mat finish and if the latter, what grade of wet/dry would you use to finish it?

Any glossy paint finish will do but you have to remember that it does not completely isolate whatever is underneath. This is why I am so anti release agent, it will leach through paint into plaster, wood or whatever else is there. I just wax wax and wax an already acceptable finish. As a rule 1000 paper scratches can be compounded out anything harsher will show.

**dtype38** · 19 Sep 2007, 21:30

Thanks for that Stephen. I understand what you say about the 1000grit and showing, but if a harsher grit is used (say 600) will it still release if its properly waxed with 1/2 doz coats?

StephenRae · 20 Sep 2007, 08:16

Yes it will work, apparently the wax fills all of the 'open' pores in the substrate. The mould will echo exactly the shape and finish. If you start off with a mat finish that is what you will end up with.
I have long since given up trying to get the original perfect I find it better to just get the shape right make a quick mould which is just strong enough to hold itself up and then put all the finishing into the first 'pull'.
If you only want one then that's the job done. If you are starting a production run then double up on the gel and laminations of the first pull and spend as much time as you have making that one perfect before you take the final mould from it.

**dtype38** · 20 Sep 2007, 20:14

Interesting... I'll give it a try :-)

trikesrule · 22 Sep 2007, 10:08

Sorry I'm so late getting back into this subject but I've been braking bones (foot) and trying to get Speedway cars ready for Daylight Day. Dtype I put as much effort as I can into a plug (or buck) as it cuts down the work later. Sanding Gelcoat can be a laborious task. I always finish with 2000 on gelcoat but if your going to paint like Steven says use something glossy but make sure it sets up darn hard. Another thing as Steven says any flaws and gloss level will be reflected in the mould. Don't use exotic products with strange chemicals in them to achieve a super high gloss. Get the best gloss level you get with paint off the gun is good enough. I use enamel paint then wait 6 weeks before touching the plug again. Got to let the chemicals out. UV helps alot but don't bake the thing. Just nice warmth is ideal. Then wax 9 times with your fibreglass shops favourite Release Wax. Tricks with Waxing. Use Terry Towel or Microfibre towels for 'off' clothes not old T Shirts. T shirts contain (and bed sheets) contain sizing this gets on the surface and interferes with the release agent. Use the correct clothe once then discard..........trikes

**dtype38** · 22 Sep 2007, 20:45

Also very interesting. I don't tend to worry too much about getting a "gloss" look because I'm invariably undercoating and painting the finished item. I was more interested in what quality of surface is needed to get a good release. The bit about getting a "hard finish" and the time for curing the paint is where I think I've been going wrong. I hadn't appreciated how important that was, or the type of cloth for polishing. Thanks for the tips.

PS If time is short, is there anything that can be painted on that goes hard quickly? Metallic paint for example.

StephenRae · 23 Sep 2007, 09:29

I can understand your indecision over what paint to use, really almost anything will do, for example if you were to brush on an oil based household paint, give it a while and follow all the waxing as described then your resultant mould and subsequent finished product would reproduce all of the brushmarks flys and runs of the original... but as you are priming and painting anyway and are probably only making one offs doing most of the cosmetic work on the finished product is easier, while as Trikes says the gel coat is a pain to sand it provides a consistant homogeneous substrate which can be finished to a showroom standard.
I used to spend hours getting the plug up to this standard only to find that the piece made from plaster or body filler or wood, despite looking perfect came out with a different gloss level or worse!

trikesrule · 23 Sep 2007, 12:08

600 scratchs won't release properly on curvy surfaces. On a flat surface you may get away with it - just. If you use PVA and pour it on and get a uniform sag across the surface (messy) this will set up quite hard if you leave it for three days and you will get quite a good surface that won't require much preparation for paint. I've just finish 'flopping' copies of some Speedway Seats that I made two Winters back (don't have a mould yet). The driver (lady) of that team dosen't fit the seat any more (darn she's added more flabby ballast). All I did was pour the PVA over 2/3 of the seat waited three days and the finish texture is 450 woven cloth - bit like uniform dimples. Laid up 2 layers of 450 CSM and made 4 slightly wider halves joined them together and made the seat bumbs 50mm wider. Resin used was Unwaxed Polyester. To finish I'll lay over 1 layer of 450 CSM and 1 layer 450 Woven Clothe - this will leave a dimpled surface again. For a bit of colour I put Hot Pink Pigment @ 4% in.

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