If wax or PVA alone is fine, why both ?  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> Composites Fabrication And Repair >> If wax or PVA alone is fine, why both ?
Page: [1]

Login
Message << Older Topic   Newer Topic >>
If wax or PVA alone is fine, why both ? - 11/11/2002 5:41:32 PM   
yclui


 

Posts: 43
Joined: 10/13/2002
From: Hongkong,
Status: offline 		Thanks for all the useful advices to my question about the incompatibility between PVA and wax in another thread. You guys are really nice. It appears that I just need to buy the right wax to solve the problem.

There is in fact another question in my mind - why use both at the same time ? After playing around with wax and PVA for a while, I came to the following understanding about the characteristics of these two mold release materials :

PVA :
1) Unaffected by polyester resin. PVA has been my only choice when making polyester molds using vacuum-formed ABS cowlings or PVC canopies as plugs. PVA protects these plugs from being attacked by polyester resin but wax doesn't .
2) Resin ( epoxy or polyester ) sticks to PVA extremely well. To make things simple, I use the same resin for making gel coats and laminating. May be it's due to the low viscocity of the resin, it tends to "bead up" on waxed surfaces but not on PVA.


Wax :
1) Finish much better than that achieved by PVA.
2) Applicable on unpolished surface. Using PVA on such surfaces almost gaurantee mold sticking .
3) Allows multiple mold releases but PVA is one-off.


Is my understanding correct and complete ?

It seems to me that the characteristics of PVA and wax complement each other. Is that the reason why experts always recommend using both at the same time ?


Thanks in advance,

Y C Lui
       Post #: 1

If wax or PVA alone is fine, why both ? - 11/11/2002 10:31:20 PM   
Ollie


 

Posts: 958
Joined: 12/8/2001
From: Punta Gorda, FL
Status: offline 		Yes, I agree with your understanding.

_____________________________

Regards, Ollie

(in reply to yclui)
       Post #: 2

If wax or PVA alone is fine, why both ? - 11/12/2002 6:07:33 AM   
boater


 

Posts: 89
Joined: 12/9/2001
From: Sacramento, CA, USA
Status: offline 		I use wax only so I can get the PVA on. I don't do production but only a few parts for myself out of epoxy. Surface finish of the final part, not a big issue because I'm gonna prime and paint it anyway. Surface finish would be an issue if I was doing commercial parts or doing polyester gelcoat that I didn't want to sand and paint. I usually only prime the plug and 400 grit wet sand it. Don't want to leave any high spots, low spots will be a high spot in the mold and I can 400 grit it off the mold. I mostly build mono boats and I have to blueprint them after molding and usually again about 3 to 6 months into the season. That means Bondo and sanding until the bottom of the hull is dead straight. I have never made enough parts to "break-in" a mold., so I always use PVA. My two cents. Rudy

_____________________________

Rudy

(in reply to yclui)
       Post #: 3

Page:   [1]
All Forums >> RC Airplanes >> Composites Fabrication And Repair >> If wax or PVA alone is fine, why both ?
Page: [1]





Jump to:


Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Member Video Posts | RCU Video Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America

Kaango.com Classifieds

0.391RCU1