gelcoat

Discussion in 'Fiberglass and Composite Boat Building' started by gaztric, Mar 29, 2018.

  1. gaztric
    Joined: Mar 2018
    Posts: 13
    Likes: 0, Points: 1
    Location: australia

    gaztric Junior Member

    Hi New guy here.

    I am going to attempt to respray the bottom of my ski boat.All is good to go upside down in back yard and sanded ready to spray.

    I have rang many a boat builder asking for help on how to go about it.And they have been helpful on the phone but some contradict the other so I am a little confused plus I only retain little amounts of information from listening.

    In writing will be better.

    So this is what I have gathered so far.I will be needing a gun or two and a helper to clean guns.Spray gun will have to have at least 2mm nozel.A pot or gravity gun is fine according to all i spoke to.
    (I have a 5.5hp compressor)

    I have 10kilos of spray gelcoat
    1kg of wax in styrene
    250ml of M.E.K peroxide 40% polyester catalyst

    Area i will be spraying is around 17 by 6ft of course towards the keel the shape changes.

    tempratures at the moment are around 65-69 in the morning during the day 95

    The boat is shaded early in the morning from 6-8am after this the temps goes up by 10am it will be about 75 at 12pm 86 and 3pm 95

    Humidity 65% during the morning and dropping as the day goes on to 20%by 3pm

    Since I am new to this i would like as much time as i can before the gelcoat cures

    Do I spray the gelcoat with waz in styrene with the first two coats?will this allow me to coat the bottom nicely and not have to worry about cleaning the gun?will it not go hard?and than with final coat i had mekp?

    Or do i apply coats with gelcoat wax in styrene as well as mekp?with one or two three coats?
    can i wait for the first coat to go hard than sand back than go over with another coat wait till hardens sand than coat again?
    or do the best with one coat?
    And yes lots of sanding buffing will be needed when im finally finished spraying

    As you can see I am a novice and quite confused.

    Thanks for the help in advanced.

    Excuse the spelling
     
  2. Blueknarr
    Joined: Aug 2017
    Posts: 1,204
    Likes: 273, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    A trick I use when spraying gelcoat;
    Small paper cups. Divide enough thinned but uncatalyzed gelcoat for one coat into 4 - 6 paper cups. Catalyze 1st cup strain and spray, catalyze 2nd and spray, 3rd... Clean gun. Set up for next coat...
    Medicine dropper works well to dispense mekp. Just don't use it again for medicine.
     
  3. ondarvr
    Joined: Dec 2005
    Posts: 2,680
    Likes: 410, Points: 83, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    You won't be able to spray a hull that size with a 2mm tip, it will spray gel coat so slow that it will get hard in the gun before you spray much of it.

    You need a 3mm tip, and it stilll won't be quick. Those tips with a pressure pot will work.
     
  4. gaztric
    Joined: Mar 2018
    Posts: 13
    Likes: 0, Points: 1
    Location: australia

    gaztric Junior Member

    Thanks for the reply's guys much appreciated.
    What would be a minimum size tip for a gravity feed gun?

    Would something like this be suited? Large Nozzle 3mm SUCTION FEED HEAVY DUTY PAINT SPRAY GUN 1 L Pot, 4 Primer, Glue | eBay https://www.ebay.com.au/itm/Large-Nozzle-3mm-SUCTION-FEED-HEAVY-DUTY-PAINT-SPRAY-GUN-1-L-Pot-4-Primer-Glue/322235253592?epid=512328736&hash=item4b06b7c358:g:gdIAAOSwgZ1XuSSd

    Or Spray Gun Paint Gun Gravity Feed HVLP 3 Nozzle 1.4mm 1.7mm 2mm Tips Air Sprayer | eBay https://www.ebay.com.au/itm/Spray-Gun-Paint-Gun-Gravity-Feed-HVLP-3-Nozzle-1-4mm-1-7mm-2mm-Tips-Air-Sprayer/121989531794?epid=2215306466&hash=item1c67248892:g:tGgAAOSwBT9Zp6X7
    Using the 2mm
    I cant seem to find and gravity feed ones like this with any larger than 2mm most i have seen are 1.8mm

    Id prefer to buy from australia atm because of time restraints

    I will be buying 2 to 3 guns so trying to keep expense down and also that one i can always have one ready.


    Also what would be a good ration to add the wax styrene ?(wax in styrene is mixed in the one tin)? would 5%-8% be okay per litre?
    there is no instructions on tins.
    Only instructions i have is on the mekp bottle saying 2-4caps per liter

    Gaztric
     
  5. ondarvr
    Joined: Dec 2005
    Posts: 2,680
    Likes: 410, Points: 83, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    Gel coat is catalyzed at 1.5 to 2%

    Most of the time wax solution is added at 2%, but you can go a bit more.

    You don't want the first gun with the 3mm tip, you want gravity feed, not siphon feed.

    Sometimes you can buy a 2mm tip and drill it out, the cheap guns here are 1.4mm and I drill them out to 2.5mm
     
  6. gaztric
    Joined: Mar 2018
    Posts: 13
    Likes: 0, Points: 1
    Location: australia

    gaztric Junior Member

    Thanks for the reply much appreciated.I should be able to do that with the gravity feed guns.
    The tin they gave me is a 1litre tin of wax in styrene. and ten liters of spray gelcoat

    I'm very much a look see person I am no good at this mixing and maths and stuff in my head or on papper.
    I remember spraying weeds farmer the poor farmer was struggling to explain to me how to work out mixes and was writing it down on papper.I said grab the jug and let me see it?

    Would you be able to explain in litres what you reckon i will need?I should be able to break it down from there with some help from my wife who's more educated than me.

    So one liter of gelcoat will require ?how much wax in styrene?2percent im not sure how to work that out in mills even with the help of a computer.
    Maybe 2%of 1000mls would that be correct?

    Hope I make sense.Thanks for the help I'm learning as I go.
     
  7. ondarvr
    Joined: Dec 2005
    Posts: 2,680
    Likes: 410, Points: 83, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    You need to add 1.5 ml of catalyst to 100ml of gel coat for 1.5%
    2 ml to 100ml for 2%
     
    gaztric likes this.
  8. gaztric
    Joined: Mar 2018
    Posts: 13
    Likes: 0, Points: 1
    Location: australia

    gaztric Junior Member

    thanks for your help

    I am a little confused catalyst is mekp is that correct?if it is I understand the mix as you have explained well.

    What about the adding of the wax/sytrene to go into the gelcoat.

    I have one ten litre tin of gelcoat spray and one 1litre tin wax in stryene whats good percent of waxin in styrene to add to one litre of gelcoat?
    Sorry for the long winded questions i just want to get it right first time.My boat is nice and of value to me.
     
  9. gonzo
    Joined: Aug 2002
    Posts: 15,408
    Likes: 1,000, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I use Duratec clear additive for spraying gelcoat. It makes it flow like an enamel, and you won't need wax. I've been using it for repairs and complete re-gelcoat jobs for about 18 years.
     
  10. Blueknarr
    Joined: Aug 2017
    Posts: 1,204
    Likes: 273, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    Now for the most important advice of all:

    1st buy a 4 x 8 sheet of Formica in the most awful color you can find. Set it up on saw horses and spray 3 coats of Gelcoat over an entire side.
    If you are unhappy with the results, flip it over and spray 3 more coats.
    Repeat as many times as nessicary.
    Practice makes perfect!

    The larger the gun's orifice, the better. I have successfully Gelcoated the bottom of vessels up to fourty feet with nozzles less than 2mm. Most of my projects can't be flipped over and the largest gun I can find that will spray up is 1.8mm. So, I make it work. One gun dealer cane to my shop to sell his line. I had him lay on his back to spray the underside of a work bench. He hasn't been back.
     
    gaztric likes this.
  11. gaztric
    Joined: Mar 2018
    Posts: 13
    Likes: 0, Points: 1
    Location: australia

    gaztric Junior Member

    You guys are great I think I finally have it sorted in my head now thank you all.Is it possible for me to private message on this forum?do i need points or credits or something or is it easier than that?
     
  12. gonzo
    Joined: Aug 2002
    Posts: 15,408
    Likes: 1,000, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    No, you just need to activate them in your profile
     
  13. ondarvr
    Joined: Dec 2005
    Posts: 2,680
    Likes: 410, Points: 83, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    If you're looking for automotive paint spraying equipment it may be hard to find tips larger than 1.8 or 2mm, if you look at the automotive primer spraying equipment the tips are larger. Or you can go to suppliers with a history of spraying gel coat like Binks, they can supply you with all of the correct tips to spray about anything. This will cost more money though.

    3M also has a nice plastic gun with disposable components that combines a gravity feed cup with a pressurized system. These work very well for spraying gel coat, and come with tips large enough to cover some square footage faster.
     
    Last edited: Apr 8, 2018
  14. gonzo
    Joined: Aug 2002
    Posts: 15,408
    Likes: 1,000, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member


  15. KD8NPB
    Joined: Mar 2018
    Posts: 104
    Likes: 20, Points: 18
    Location: South Carolina

    KD8NPB Senior Member

    3M PPS 16580 kit,
    w/ red 2.0 tips

    Standard cups holds 650 ml (22 oz).

    You can reuse the tips a few times if you don't soak them for too long.
     
Loading...
Similar Threads
  1. JackyJ243
    Replies:
    8
    Views:
    944
  2. Nachtvlinder
    Replies:
    2
    Views:
    351
  3. Scuff
    Replies:
    12
    Views:
    1,062
  4. doogymon
    Replies:
    12
    Views:
    744
  5. wesley Sherman
    Replies:
    14
    Views:
    1,923
  6. bedfordd
    Replies:
    9
    Views:
    1,516
  7. E350
    Replies:
    7
    Views:
    2,871
  8. bch
    Replies:
    6
    Views:
    1,078
  9. Charlie A Bess
    Replies:
    13
    Views:
    1,798
  10. Crayolo
    Replies:
    5
    Views:
    1,591
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.