stevebubs
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| posted on 29/11/05 at 09:45 PM |
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Making a mould & bulge
OK...had a bit of a read around the subject but still not 100% on what bits I need.
Buck will be ready in a week or 2 and want to make sure I have the rest of the bits around so I can plough straight on over the Crimbo break
So far, I think I have identified everything I need to make a mould and bulge that's approximately 22inx22inx1.5in
Does the following shopping list look OK?
The Shopping List
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Chopped_
Strand_Mat__CSM__Grade_1_42.html
2kg Roll CSM 300g Grade 1
5kg Roll CSM 600g Grade 1
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__General_Purpose_Res
ins_6.html
5kg General Purpose Resin
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Pigment_Pastes_
500gm_Tins_70.html
500gm Pigment Paste (RAL 1023)
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Clear_Gelcoat_49.html
1kg Clear Gelcoat
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Paddle_Rollers_121.html
50mm Paddle Roller
140mm Paddle Roller
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__APW_Soft_Release_Wax
_81.html
PVA (Polyvinyl Alcohol) 1L
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Farecla_G3_85.html
Farecla G3 400gm tube
[edited to add swap wax for PVA]
[Edited on 30/11/05 by stevebubs]
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stevebubs
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| posted on 29/11/05 at 09:48 PM |
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Making the mould
Does this method sound right?
Method
ensure air temperature is over 5 deg C
Wax up the buck and polish off
Repeat 3 times
Mix up 500g of gelcoat, and spread onto buck using paintbrush
Also put some gelcoat on a scrap piece of plastic
Wait until gelcoat is firm to touch but still tacky (use gelcoat on scrap plastic to test)
Place layer of 300g CSM over bulge, trim slightly oversize.
Mix up about 750g Resin and dab onto the CSM. Roll out bubbles
Place layer of 600g CSM over previous layer
Mix up about 1kg resin and dab onto CSM. Roll out bubbles
Do another 2 layers of 600gm, no gap between between layers except to mix up the resin and roll out the bubbles
Leave 48+ hours to set
Turn over and prise buck out of mould
[editted to remove gaps between layers and add rolling action]
[editted to add gelcoat stage]
[editted to add temperature check]
[Edited on 30/11/05 by stevebubs]
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emsfactory
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| posted on 29/11/05 at 10:01 PM |
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I have been making cycle wings lately. I am not a pro but here is what I have found.
You dont have to wait between layers of glass. You dont want the resin to be set when you put another layer on. You want it all to blend together.
Dont cut the glass with a knife or scissors, tease the glass mat apart into the required size. this way you wont see the edges of the glass in the
finnished article. I tear the glass mat over the edge of the bench, just like tearing paper.
For the gel, its ready when you can press with reasonable force and only leave a finger print. Again you want the resin to merge with the gel. The
risk is that its not set enough and peels off your buck (mould).
If you put some of the gel you mix onto something scrap at the same time you can test this and not risk damaging your cast.
When the gel is ready paste resin all over to get it mixing, then a layer of glass then more resin. use the brush and stipple it in, try for an even
coating. Get a roller and roll the air out. Then do the next layer.
Easy peasy.
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Chippy
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| posted on 29/11/05 at 10:05 PM |
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If you are going to use CFS to get your supplies, they also do a very good booklet that describes how to use Glass fibre, worth getting a copy. I
would also recommend not using the release wax but use the PVA instead, much easier break out. Have fun. 
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stevebubs
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| posted on 29/11/05 at 10:27 PM |
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quote:
Originally posted by emsfactory
I have been making cycle wings lately. I am not a pro but here is what I have found.
You dont have to wait between layers of glass. You dont want the resin to be set when you put another layer on. You want it all to blend together.
Dont cut the glass with a knife or scissors, tease the glass mat apart into the required size. this way you wont see the edges of the glass in the
finnished article. I tear the glass mat over the edge of the bench, just like tearing paper.
For the gel, its ready when you can press with reasonable force and only leave a finger print. Again you want the resin to merge with the gel. The
risk is that its not set enough and peels off your buck (mould).
If you put some of the gel you mix onto something scrap at the same time you can test this and not risk damaging your cast.
When the gel is ready paste resin all over to get it mixing, then a layer of glass then more resin. use the brush and stipple it in, try for an even
coating. Get a roller and roll the air out. Then do the next layer.
Easy peasy.
Thanks for the hints.
Should I perhaps use gelcoat as the first layer then when making the mould?
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craig1410
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| posted on 29/11/05 at 11:05 PM |
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Steve,
Be careful you don't mix up too much resin at once because it is an exothermic reaction (ie. gives off heat) and will cure too fast in the pot.
1Kg at a time seems to much to me unless you were doing the side of a boat or something where you could slap it on really quick.
The other thing is to get some of the industrial marigold gloves from CFS with your order to protect your hands. These are much better than the usual
latex gloves which tend to fall apart when the going gets sticky. CFS also do some cut down paintbrushes fairly cheaply which might be worth getting.
Oh, and don't forget to get plenty of acetone for cleaning resin off tools, hands, gloves etc afterwards.
One final thing which I learned a little while back is that Gellcoat will only cure hard in the absence of air and will remain tacky when air curing.
This is fine on the inside of a mould but if you ever need to use gellcoat on the outside (eg. for repair purposes) then you need to add some wax to
the gellcoat to form what I think is called Flowcoat. Check the CFS booklet but I think you use 5% wax in the gellcoat to ensure that it doesn't
stay tacky when cured.
Have fun!!
Craig.
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Simon
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| posted on 30/11/05 at 01:04 AM |
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quote:
Originally posted by stevebubs
Does this method sound right?
Wax up the buck and polish off
Repeat 3 times
GELCOAT HERE
Place layer of 300g CSM over bulge, trim slightly oversize.
Mix up about 750g Resin and dab onto the CSM. Roll out bubbles
Place layer of 600g CSM over previous layer
Mix up about 1kg resin and dab onto CSM. Roll out bubbles
Do another 2 layers of 600gm, no gap between between layers except to mix up the resin and roll out the bubbles
Leave 48 hours to set
Turn over and prise buck out of mould
[editted to remove gaps between layers and add rolling action]
[Edited on 29/11/05 by stevebubs]
Steve,
As Craig says, gelcoat only sets when sealed (well it will "airdry, but it takes ages).
What is helpful, is get an old piece of thickish plastic and "wet" the matt away from the job to ensure it's wet both sides
(therefore all the way though) before laying up.
I didn't use any lightweight matt with mine, but it's a good idea for getting round tighter corners.
As for leaving 48 hours, it's gonna depend on workshop temp, but it may well still be green - a visual inspection should help. The resin will be
almost white (when it's not green )
The CFS catalogue is very useful, so is Steve Gusterson's site http://www.locostbuilder.co.uk.
ATB
Simon
[Edited on 30/11/05 by Simon]
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emsfactory
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| posted on 30/11/05 at 01:10 AM |
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For a nine inch wide cycle wing I use 1 baked bean tin of gel and 1 baked dean tin of resin. I put on two layers of 450g/m matt and have none left
over. Using a kilo (possibly 2 and a bit baked bean tins) may be too much.
Yes use a gel coat to make your mould too.
Try and practice on something first. I did a bucket. If it dont work who cares but it did so ive got an extra bucket.
Swish.
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scotty g
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| posted on 30/11/05 at 07:58 AM |
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Don't want to teach anyone how to suck eggs here but no one has mentioned the most important thing for his shopping list........catalyst,
without it your gel and resin will never set, 2% catalyst to resin is about right but you might want more in this weather, also you need to double
this amount for gel.
You should deffinately have a practice session first as a little experience is vital.
You would be better off mixing all the resin up at once and getting the job done in one hit.
The key to this is preparation, get the gel on and while thats going off you can get your resin in a bucket ready, get all layers off matt cut (or
torn) to the right size, brush cleaned and drained of acetone etc.
You will surprise yourself at how easy it actually is, don't worry about it, it aint rocket science.
Godd luck mate.
Scotty G.
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stevebubs
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| posted on 30/11/05 at 09:44 AM |
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quote:
Originally posted by scotty g
Don't want to teach anyone how to suck eggs here but no one has mentioned the most important thing for his shopping list........catalyst,
without it your gel and resin will never set, 2% catalyst to resin is about right but you might want more in this weather, also you need to double
this amount for gel.
You should deffinately have a practice session first as a little experience is vital.
You would be better off mixing all the resin up at once and getting the job done in one hit.
The key to this is preparation, get the gel on and while thats going off you can get your resin in a bucket ready, get all layers off matt cut (or
torn) to the right size, brush cleaned and drained of acetone etc.
You will surprise yourself at how easy it actually is, don't worry about it, it aint rocket science.
Godd luck mate.
Scotty G.
I missed catalyst off as all the resins and gelcoats are supplied with it as standard. Will add some extra.
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stevebubs
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| posted on 30/11/05 at 09:48 AM |
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OK. I've added the gelcoat stage. Any more recommendations are welcome ?
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scotty g
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| posted on 30/11/05 at 01:07 PM |
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Ok Steve, now the gel is on, get everything else ready. If the gel is still wet after a couple of hours get the wifes hair dryer on it and warm it up
a BIT.
When you're ready to lay up the matt bung some resin on the gel first, then a layer of matt (don't paint the resin onto the matt but
rather "stibble" it on like you're trying to push the resin through the matt. Once wet get the next layer on and wet that out, now
you can roll it.
When the air is out of the layers crack straight on with the next two layers, roll and let them all cure together. Job done.
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stevebubs
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| posted on 30/11/05 at 01:47 PM |
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starting to sound like I might have a chance of doing this without F*cking it up (famous last words!!)
Any more suggestions for the shopping list?
Stephen
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Schrodinger
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| posted on 30/11/05 at 02:22 PM |
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I have a book on making GRP moulds etc. if you would like to borrow U2U me
IIRC it recommends putting 2 layers of gel coat on and leaving overnight before laying on the matt and resin.
Keith
Suffolk
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scotty g
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| posted on 30/11/05 at 02:59 PM |
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In an ideal world it would be best to leave overnight but in reality (and industry) this is rarely the case.
In every GRP workshop i have ever encountered the gel will be layed up on between 1 and 4 hours of application.
Time is money and all that!
I'm not saying that Steve shouldn;t leave it over night, just that its not really that critical for a home made bonnet bulge as long as the gel
HAS set.
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stevebubs
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| posted on 30/11/05 at 03:13 PM |
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In a home environment, I'd probably leave it - apply the gelcoat Friday night after work and then go out on the p!ss.
Finish off Sat afternoon when I've recovered 
PS Shopping list updated and called the order in to CFS ; waiting for a call back with the price....
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Avoneer
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| posted on 30/11/05 at 05:08 PM |
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And it's supposed to be over 5 degress air temp or it will never set.
Smells a lot too.
Don't cock up your resin/catlyist mix as it may never set, or set too quick.
Get lots of latex gloves as it's bloody messy.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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stevebubs
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| posted on 30/11/05 at 05:32 PM |
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I buy triple packs of gloves 100 from Costco - 300 should do the trick!!
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stevebubs
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| posted on 30/11/05 at 05:32 PM |
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Have to choose the right weekend and install a heater, too then!
Don't think SWMBO would let me do it in the dining room 
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chriscook
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| posted on 6/12/05 at 04:27 PM |
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Be careful not to get air bubbles in the gelcoat - i ended up with quite a few in mine - they'll fill ok but would have been better if they
weren't there in the first place.
Oh I used gel coat on the mould too - just don't colour it the same as you want the finished part. So you can see where you have put gel coat
when making the final one. I used wax AND pva and had no problem getting them apart. (On a large mould I once just used wax and two transit vans
couldn't part mould and buck so the buck had to come apart!)
Chris
[Edited on 6/12/05 by chriscook]
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stevebubs
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| posted on 6/12/05 at 04:35 PM |
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quote:
Originally posted by chriscook
Be careful not to get air bubbles in the gelcoat - i ended up with quite a few in mine - they'll fill ok but would have been better if they
weren't there in the first place.
Oh I used gel coat on the mould too - just don't colour it the same as you want the finished part. So you can see where you have put gel coat
when making the final one. I used wax AND pva and had no problem getting them apart. (On a large mould I once just used wax and two transit vans
couldn't part mould and buck so the buck had to come apart!)
Chris
[Edited on 6/12/05 by chriscook]
Any tips on avoiding air bubbles?
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scotty g
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| posted on 6/12/05 at 06:54 PM |
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Aoiding air bubbles.
Just roll a lot with the paddle roller, air bubbles tend to gather in corners and tight bends.
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