Releasing fibreglass from the mould, any tips?

[dtype38]

Originally Posted by trikesrule

..... 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. .......... For a bit of colour I put Hot Pink Pigment @ 4% in.

Oh dear, I now have a picture in my head of hot pink dimpled flabby ballast, dressed in a pva uniform, and sagging evenly across a messy speedway seat.

Fibreglassing is obviously only for the brave in Aus!

But thanks for the help guys.

[trikesrule]

Yeh it's a heck of a picture lol..........trikes

[phansa88]

when i made race yachts and boat sand the plug through the sanding grades
600 -1200 then polish with electric polisher and compound rough medium and fine. t-cut then wash wipe dry , 3 layers of wax leave 12hrs between each one ,then pva.
then gel and glass up leave to cure say two days then release
p.s i always put a air connector into the mould when laid up so i could pop the mould of the plug .also helps when doing the moldings just a piece of tape over the hole every time.

[yukspeed]

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!

Hi I use clutch/brake cleaner, works mint on glass, door squares, and paint.
Yukspeed Rally Spares.

[GORDON STREETER]

Originally Posted by yukspeed

Hi I use clutch/brake cleaner, works mint on glass, door squares, and paint.
Yukspeed Rally Spares.

He's probably got it off in the last 6 years !

[SidewaysFeltham]

Originally Posted by GORDON STREETER

He's probably got it off in the last 6 years !

If not, then he ought by now (hopefully!) to have seen his urologist!

[dtype38]

I don't even own it any more!

[terence]

Good advert though.

[sime1070]

G'day...
My first attempt at fibreglassing in a mold hasn't turned out so good - the actual fiberglass is great, popped out of the mold no worries and is nice and strong BUT some of the gelcoat has remained in the mold and not on the piece... Was told to wax several times before I applied the gelcoat which Idid but maybe not enough? Don't know...
Has ended up wrinkled or absent in places and I am not sure why... I am thinking a) not enough waxing b) improper application of the gelcoat (brushed on) or c) something else! Can anyone give some pointers please?
Also what do I clean the mold with before I try again?
Thanks in advance for any advice!
Cheers,
Simon

[JohnD]

Well done, sime! It's very satisfying to get that first copy out isn't it?

I'm afraid all I can suggest is MORE waxing. I tried some PVA that a local GRP workshop gave me but it just beaded on the mould surface, so I had no confidence that it would form a protective layer. I've mentioned carnauba wax as the best type to use, and of course never a silicone wax. Take time to do this, leaving the last coat of wax for 24 hours to properly harden before applying another, and go for at least five coats. Try to go around the mould in a different way each time to avoid missed sections.

Repairing your mould: sand off the residual gel coat fragments, then smoth with up to 1200 grade and rewax. If there are holed in the mould surfacethen fill with Plasticine! Smooth with a wet finger and wax.

[dtype38]

Yeh, agree that waxing and waxing some more is needed. When you're bored with waxing and buffing, then do it some more till you're really really, bored. Personally I use my compounding machine with a fleece mop on it to do the buffing, takes the arm ache out!

As for pva release agent, I've always used it myself. I find it critical to make sure there are no hand prints of blemishes on the wax coat, then put it on as thin as you possibly can. I use a piece of very soft cloth and wipe it on. If you do get an area that wrinkles or beads then wipe it off and redo it while its wet. Once it's dry it's quite fragile so trying to put more on can just make it ruck up more. Personally I do find it difficult to get a nice smooth coat, but I prefer to put up with some wrinkling and sand it out of the final item rather than risk it sticking.

Brushing on the gel coat is fine, but if you do use pva, do it as gently as you can. I do my gel coat in two thin layers rather than one thick one which makes it easier. (if I'm painting the finished item then I use two different shades of gel coat, so that when I'm sanding joints and wrinkles I can tell how far through the gel coat I am).

I'm a little surprised your gel coat separated from your item rather than the mould. Suggests you might have let it cure a little too long before adding your mat coats. You want to do that while it's still tacky (also paint the gel coat with resin and do a tissue layer before adding the first layer of mat - this makes it easier to avoid trapped air layers or bubbles.)

Good luck with your next attempt :-)

[TR.]

Personally found waxing with no PVA has done the job for me in the past for wetlay fibreglass. We use the stuff in the link below in work, typically 5 layers 15 min cure between off and on again. PVA is a nightmare to not have any drips/runs/brush fibres in from experience, but doesn't really matter if the part is to get painted I guess.

http://www.specialtyproductsco.com/s...ypage.tpl.html

Cracking idea of two different coloured gel coats for depth check, will remember that one!

[winkle]

I have found it best to put at least 6 layers of carnuba wax and polish up between coats with a towel.

I have had success using the blue PVA on small moulds, but dilute it with water and spray on a few coats to avoid brush marks and sags.

Good luck

Steve

[JohnD]

TR,
Is that your company, SPC?
You offer a "semi-permanent" releaser - is that much more expnsive than just wax? Or difficult to apply?

I've previously relied on the generosity of local GRP manuafacturers to sell me wax, matt and resin. It's good to find a specialist supplier, in case they can't help.
John

[Trikes]

Crocodile and Sticking are both signs of a contaminate on the Mold surface. It may have looked great but the ultimate test is the 'clean release'.

Sime prepping a mold is a time expensive laborious job. But attention paid here is most rewarding later so don't rush it and every time you think that will do it probably won't.

One must do the hard yards to avoid the problems you've encountered.

Step one) If the Moud hasn't got a perfect and I do mean perfect unflawed finish use PVA. If it has, apply 5 coats of wax, allow it to set up as in dry (follow the manufacturers directions to the letter and beyond) waiting at least a couple of hours between coats in Summer and up to a couple of good weather days during the cooler months but not Winter. Moisture and Humidity is a problem during the colder months. Use brand new straight from the pack Microfibre Cloths for off cloths. Here's the thing, you can only use them once then throw them in the Engine Dipstick checking pile.

Wash the Mold with Acetone before Waxing and wait a few days before Waxing. Chemically clean can only be achieved with Acetone. Thinners won't do. Also you must wear Disposable Gloves. Never touch the Mold with bare skin. Have to move the Molding. Put Disposable Gloves on. Picking up the Mold Cover, put Gloves on before touching the Cover.

Five Coats is the minimum. Not using the Mold for a while or a few hours cover it with a brand new lite weight Shower Curtain. Peg or tape the the over hanging bits so no dust etc can get in but don't let the Cover touch the Mold. You want the Mold to still be able to breathe. Wait a week or two before use.

Between Lay Ups add a couple of coats of wax just for the luxury of it.

Bloomin Heck! I hear you say, that's excessive! But no, it's not.

Silicone is a common Contaminant. The best way to get rid of Silicone or suspicion of it is with Steam. Yep Steam. You can Acid wash your Concrete Floor a day or so later too, just to kill or get rid of everything else. So Hire a Karcher or the like that sprays really really hot water, squeegee the water out and come back in a week to start the Mold Repairs......

Now it's time to start the repairs to your Molding. Wear Gloves and Long Sleeved Clothing at all times. Don't go leaning on the Mold doing the Repairs. If you get tired, cover the Mold then stop and rest away from the Mold. Cleanliness is Godliness.

Silicone's are a Glasser's nightmare and you have some on your Mold.

[Al Weyman]

I'm just about to make another front spoiler for the 2nd Gen Camaro and also want to make a pair of arch extensions for Project IROC. For the arches I need to make two moulds using the pair of rear quarters that came with the car as a puck. My question is Ive been told by someone who does a lot of this work that in a similar way that someone previously suggested using brown packing tape on the mould to mask imperfections he covers the entire mould or puck in signmakers vinyl prior to waxing etc. This would be far easier for me to do than painting, fine filling and preparing so I would like to know has anyone else used vinyl for this purpose. I would think it would be an ideal method if it works when taking moulds of existing cars like the Aston Martin example above as the vinyl would protect the original panel.

[terence]

Dont forget the resin will generate heat whilst curing Al, that might affect the vynal.Spend a bit of time on the bucks themselves.

[Al Weyman]

Ok I hear what you say, the vinyl I would use can take a lot of heat as that's how you stretch it in in fact some people even use a gas torch!

[gt917]

Al,

I would test a small sample first. Have used it quite a bit myself over the years, BUT, have had pickling problems sometimes leaving a sticky residue of the adhesive after the resin/heat attacked the tape surface. Nice ripple/crinkly finish on the gelcoat !!!!!!!!!!!!!!!