On 11/11/02 7:42 AM, "yclui_hk" <[EMAIL PROTECTED]> wrote: > 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. Hi All,
As a modelmaker I have a bit of experience using wax and PVA as a mold release. It is with out a doubt possible to have a part release from the mold using only wax, PVA is added insurance. PVA can be beneficial to act as a barrier between your waxed pattern and casting material. This is good for silicone rubber molds because it is very sensitive to contaminants and PVA can seal them out. PVA can be thinned with water or Methyl alcohol for spraying, and if you have the equipment spraying is nicer than brushing. By spraying it on you should be able to use it over any wax. The key is to start with very very lite coats. Thermals, Don Vetter > 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 > > > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and > "unsubscribe" requests to [EMAIL PROTECTED] Please note that > subscribe and unsubscribe messages must be sent in text only format with MIME > turned off. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
