Releasing fibreglass from the mould, any tips?

[Al Weyman]

I have trimmed it, trial fitted it and its now primed up awaiting the top coat, well pleased.

[Notso Swift]

Trikes, I think there are a lot of successful pulls on 10/10's!
I must say the Racing Tech Forum has got to be the best for people giving up some really good knowledge. This topic alone is a prime example. I have previous stuffed up glass work to my credit and have avoided doing more as a result, but now I might look at doing some again.

[StephenRae]

Congrats Al........You will never know whether you needed the PVA or not! or how much better the finish would have been without the damnable stuff

[Al Weyman]

Actually Stephen I don't think it affected the finish at all as I just cleaned it off with cellelouse thinners and it was fine, nice smooth white gell coat. Maybe it was because i sprayed it on as suggested here, I just put it in a little household spray and hit it, I was actually expecting it to pool on the wax but it did'nt, extrodinary stuff.

[dtype38]

Er... I was told to keep cellulose thinners well away from fibreglass/moulds as it softens the resin. Anyone verify/debunk that please?

[Al Weyman]

I would say not personally like I also read on the fibreglass suppliers site I only needed PVA release agent and not wax as well, not true as pointed out here and I found out to my cost. They probably want to sell you some Acetone based cleaner at twice the cost of celleouse thinners which I use a lot in my signmaking especially for removing old vinyl glue whereas I could pay four or five times the amount for 3M glue remover to achieve the same.

I really rubbed hard at the finished product with a thinners soaked rag and it did not effect the gel coat one iota infact a perfect finish for a nice coat of primer in fact which I could probably have got away without.

What I will say is you are probably right if you attack it with the thinners before it has cured properly because it makes a very effective tool and brush cleaner.

[dtype38]

Originally Posted by Al Weyman

What I will say is you are probably right if you attack it with the thinners before it has cured properly because it makes a very effective tool and brush cleaner.

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!

[StephenRae]

Both acetone and cellulose thinners seem to have the same detrimental effect on new gel coat, I resorted to cellulose thinners to remove residual glue from an 8 year old gel coat with no ill effects.
Petrol works on sticker and tank tape gunge but don't leave it on too long.

[Al Weyman]

D-Type, pay attention in class, if you see my post i said I use the celleouse thinners to remove the glue residue from vinyl graphics. You can pay a lot for 3M remover from your local supply shop or if you want to go mad by a Vinyl Zapper from Snap on or Jag Sign Supplies for over £300 plus vat, I have one and they are excellent, you think they are a waste of money till you try to remove reflective or chrome vinyl as they are something else again! They take off the vinyl and also the glue and turn them into a powder.

PS I agree petrol is OK as well especially if the paint finish is not 2 pack, it does stink though, White spirit is OK as is meths but harder work but required sometimes if the substrate is a bit suspect to damage from the others.

[jaysalv]

thanks for the advive guys davrian came out excellent in the end there are pictures of the whole project available to look at if interested on my site

[Speedy1]

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]

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]

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

[trikesrule]

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]

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]

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]

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]

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]

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]

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]

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

[trikesrule]

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]

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]

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]

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.