Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors

Go Back   Boat Design Forums > Construction > Boatbuilding
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read Most Recent Posts Gallery Images Search

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 04-26-2010, 04:15 PM
sweetwater sweetwater is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 6
Location: Destin, FL
Sealing a plug

I've got a question for those with some experience making/fairing plugs. We're making a plug that has several skin coats of door skin/luan and using bondo and thickned epoxy resin to fair. Just recently with the increase in temp and humidity the exposed wood (wood that has been sanded down past the bondo and epoxy) has distorded a little. It's only obvious to the touch when running your hand over it quickly.

My question is should I seal the whole plug with epoxy resin or something. Or maybe lay a layer of glass. I'm hesitant to lay glass because I feel that it will just add more work to cover the print through.

I was planning on priming, then using duratec spray fair but I'm not sure if this will "seal" the absorbative qualities of the open wood grain. Anythoughts?

I'm attaching a picture of the plug.
Attached Thumbnails
Sealing a plug-img00192.jpg  
Reply With Quote


  #2  
Old 04-26-2010, 04:27 PM
Lurvio's Avatar
Lurvio Lurvio is offline
Mad scientist
 
Join Date: Jul 2009
Rep: 249 Posts: 283
Location: Mid of Finland
Is the wood just coarse to the touch or has it shrunk or swelled?

I haven't done molds like that, but I'd say if the wood hasn't gotten water on it, just recoat the whole thing with epoxy.
__________________
Hopefully creating something useful, since 1983.
Reply With Quote
  #3  
Old 04-26-2010, 04:39 PM
sweetwater sweetwater is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 6
Location: Destin, FL
The wood isn't necessarily course to the touch, it has just "warped/raised" where exposed. Just a few days ago this wasn't the case, the plug was almost fair. I assume that with an increase in moisture and the heat added through sanding caused the exposed wood to raise due to expansion.

I'll probably end up just coating in epoxy.
Reply With Quote
  #4  
Old 04-26-2010, 04:43 PM
apex1
Guest
 
Posts: n/a
Quote:
Originally Posted by sweetwater View Post
My question is should I seal the whole plug with epoxy resin or something. Or maybe lay a layer of glass. I'm hesitant to lay glass because I feel that it will just add more work to cover the print through.
You MUST seal all open surface of the wooden structure (on the "backside" of the plug) it will "work" otherwise.

Using simple exterior house paint in three layers should do the trick.


Regards
Richard
Reply With Quote
  #5  
Old 04-26-2010, 04:53 PM
sweetwater sweetwater is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 6
Location: Destin, FL
By "backside" of the plug do you mean the exposed outer surface and the "internal" surfaces. I'm afraid it would be too late to coat the inside but the outside can and will be coated with something.

Question with using exterior house paint. Should it be used with a primer so that the coatings bond to the wood and are not pulled away from the plug when pulling off the mold?
Reply With Quote
  #6  
Old 04-26-2010, 05:05 PM
apex1
Guest
 
Posts: n/a
Quote:
Originally Posted by sweetwater View Post
By "backside" of the plug do you mean the exposed outer surface and the "internal" surfaces. I'm afraid it would be too late to coat the inside but the outside can and will be coated with something.

Question with using exterior house paint. Should it be used with a primer so that the coatings bond to the wood and are not pulled away from the plug when pulling off the mold?
God NO!

Do NOT apply that paint on the surface of the mould!!!!

You did already one mistake not to seal the inner sides of your plug (there the paint helps).
The surface was sanded down into the wooden structure (that was another mistake), and should have been immediately sealed by Epoxy or whatever stuff you use for the coating.
Leaving wood open on the backside of your "nice" surface will always end up in a distorted plug once the humidity changes.

ALL the structure of the plug has to be sealed against humidity! So turn it and do that first, you otherwise have a never ending problem.

Regards
Richard
Reply With Quote
  #7  
Old 04-26-2010, 06:22 PM
Landlubber's Avatar
Landlubber Landlubber is offline
Senior Member
 
Join Date: Jun 2007
Rep: 1793 Posts: 2,632
Location: Brisbane
Duratec is the name of the most commonly used plug surface preparation products I am aware of. Applied over whatever you have extablished, and done as directed, you will have a perfect surface to make your mould from.

...and yes, as Apex says, also protect the inside asap with some sort of cheap coating to protect the plug even though it will be destroyed very soon, any moisture entering the plug wil distort it, so a few litres of cheapo paint is money well worth spending.
__________________
I am not a complete idiot.......some parts are still missing
Reply With Quote
  #8  
Old 04-26-2010, 06:30 PM
sweetwater sweetwater is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 6
Location: Destin, FL
You had me wondering as well with the house paint. I really couldn't comprehend applying house paint to the mould surface. Kind of caught me off guard. I now realize that by "backside" you meant surface inside the plug.
I think we just had our verbage crossed.

As I said, I am planning on re-coating in epoxy, realizing that I should have sealed immediately following the exposure of the ply.

I guess my original question was how far should I take it. A layer of glass, then high-build, etc.. or just epoxy rolled on to seal then procede.
Reply With Quote
  #9  
Old 04-27-2010, 06:51 AM
apex1
Guest
 
Posts: n/a
Depends on how much stability you need to achieve, if glass fabric is recomended or not. Usually it is a waste of money, and additional labour to fair out the fabric pattern (print through).

If your plug ist too flimsy to be turned over and sealed inside, it might be worth the effort. On the other hand, it will be cheaper I guess, just to stabilize the climate conditions until you have your mould made.
If there (structurally) is no glassing needed, you are fine with Duratec as Lubs mentioned, and Ep would be overkill.

Regards
Richard
Reply With Quote


  #10  
Old 04-27-2010, 07:36 AM
sweetwater sweetwater is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 6
Location: Destin, FL
Thanks for the advice. We'll be covering with duratec.
Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
sealing wood computeruler Boatbuilding 18 08-19-2008 12:22 AM
Mold sealing Agewon Materials 6 07-26-2007 09:01 PM
Sealing a motor well? RHough Sailboats 3 12-03-2005 02:32 AM
Sealing with Silicone? Ok J Powerboats 16 06-11-2005 09:45 PM
sealing fiberglass alvingra Boat Design 2 08-25-2004 05:52 PM


All times are GMT -4. The time now is 02:25 PM.


Powered by: vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2014 Boat Design Net