New mold, any bulletproof release method?

Discussion in 'Fiberglass and Composite Boat Building' started by mrdebian, Jul 9, 2022.

  1. mrdebian
    Joined: Apr 2021
    Posts: 76
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    Hi all,

    I read a lot of posts about recommended methods of waxing a new mold but nearly everyone ads something new or a different way to do it.
    I've got a relatively small mold (new kayak rim) but has many round shapes and some 80o angles.

    What I am planning to do is to wax every 30 minutes and up to 12 times.
    Then is not clear to me what is the recommended method with PVA. Do I need to spay it several times and ideally at what intervals to achieve the best possible release?

    Any other method that you tried and was a 100% success is more than welcome.

    Thanks a lot
     
  2. fallguy
    Joined: Dec 2016
    Posts: 6,779
    Likes: 1,387, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I used partall #10 wax and spray. They make a couple different sprays; one is water based iirc.

    But you wax and spray, only for you, variation in the spray translates to the final product, so I have never worked to that level of detail and so my post is sort of too basic.

    see if @ondarvr has a method and if so, follow it
     
  3. wet feet
    Joined: Nov 2004
    Posts: 1,058
    Likes: 241, Points: 63, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    You could use a mould sealer before six coats of wax. Alternatively,you might look at the instructions issued by the wax manufacturer.PVA may help,but be aware that it may reduce the quality of the surface texture a bit and there is more than one variety-alcohol based or water based and you need to keep to one or the other.
     
  4. ondarvr
    Joined: Dec 2005
    Posts: 2,863
    Likes: 519, Points: 113, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    Read the can of wax and do what it says. You can wipe on PVA easily, put a small amount on the rag and wipe in small circles until it dries almost immediately behind the rag. This will be quick and have a good surface. If the waxing is done correctly you don't need PVA, it's an insurance policy if you didn't get it waxed right.
     
    fallguy likes this.
  5. mrdebian
    Joined: Apr 2021
    Posts: 76
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    Just an update that I did 11 coats of wax with 20-30 minutes between them (at 25-28oC) and then I used as @ondarvr recommended a small rag with a little bit of PVA. I released the rim today after about 24hours and came out super easy.

    Thanks a lot
     
    ondarvr and fallguy like this.
  6. Tedd McHenry
    Joined: Feb 2020
    Posts: 50
    Likes: 8, Points: 8
    Location: Surrey, BC, Canada

    Tedd McHenry Junior Member

    Not specifically wax-related but, if your concern is getting the part out of a deep female mold, I've seen a clever method used on racing car molds. Build a garden hose fitting into the mold, ideally at the deepest point. Then, when it's time to remove the part, attach a hose and just crack the valve. After a few minutes the part will pop out.
     
  7. rnlock
    Joined: Aug 2016
    Posts: 242
    Likes: 65, Points: 28, Legacy Rep: 10
    Location: Massachusetts

    rnlock Senior Member

    I've heard of the same with compressed air, but if this is along, skinny part I don't know how much it will help.
     
    redreuben likes this.
  8. rxcomposite
    Joined: Jan 2005
    Posts: 2,626
    Likes: 503, Points: 113, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Waxing will not cut it if the mold is new. The mold is not yet 100% cured and there are volatile styrene in it which will migrate and attack the first layer of laminate. It is our practice to fully cure. We place it in an 250F degree oven for about an hour, expose it in a hot sun for two days, or leave it in a hot well ventilated room for a week. Only then can it be prepped. You can smell the styrene evaporating as you heat it up. If you cannot smell it anymore, it is probably good to go.
     
    mrdebian and fallguy like this.
  9. Tedd McHenry
    Joined: Feb 2020
    Posts: 50
    Likes: 8, Points: 8
    Location: Surrey, BC, Canada

    Tedd McHenry Junior Member

    Compressed air isn't such a good idea because it stores energy in compression. Your part could fly across the shop! Water is much better.
     
  10. rxcomposite
    Joined: Jan 2005
    Posts: 2,626
    Likes: 503, Points: 113, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    We had success with the same method. We used compressed air for small part. A short burst of high pressure. We covered the end of the fitting with a small piece of packing tape so that the gel coat will not enter. For a very large mold like a hull 20 m long, we had 2 fittings fore and aft. with 30 psi of water, it cracked/released from the mold. A little cajoling with a rubber mallet released some stubborn part but mostly just prying out the flange will work as soon as it cracks open.
     

  11. Gasdok
    Joined: May 2020
    Posts: 24
    Likes: 0, Points: 1
    Location: Florida

    Gasdok Junior Member

    Absolute best thing I've found is to apply lightly waxed freezer or parchment paper to the release surface. It's inexpensive and can be applied with spray adhesive. It's best to use small 1 ft sections to minimize wrinkles use a Bondo spreader or if you're cheap a credit card to smooth.
     
Loading...
Similar Threads
  1. mrdebian
    Replies:
    3
    Views:
    95
  2. Bigtalljv
    Replies:
    33
    Views:
    524
  3. mrdebian
    Replies:
    17
    Views:
    595
  4. aaronhl
    Replies:
    22
    Views:
    693
  5. John Rivers
    Replies:
    42
    Views:
    1,385
  6. Jesus Torres
    Replies:
    0
    Views:
    370
  7. Oceanview boatworks
    Replies:
    15
    Views:
    1,119
  8. mrdebian
    Replies:
    37
    Views:
    1,798
  9. mrdebian
    Replies:
    7
    Views:
    840
  10. mrdebian
    Replies:
    3
    Views:
    902
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.