Home |
Search |
Today's Posts |
#21
posted to rec.boats.cruising
|
|||
|
|||
Getting to the bottom of it... (Ablative question)
On 24 Aug 2006 21:24:02 -0500, Dave wrote:
Epoxies must be sealed off from air exposure in order to cure. That is not true, you are thinking of polyester resin, not epoxy. They are not the same. |
#22
posted to rec.boats.cruising
|
|||
|
|||
Getting to the bottom of it... (Ablative question)
Exactly right Wayne!
Some Polyester and Gelcoat sold for car and boat repairs in hardware stores contains wax, but commercial gelcoat used in moulds and polyester resin used for laminating does not. For a proper cure, polyester must be shielded from the air and the wax floats to the surface and inhibits reactions with the air. Applying wax paper or plastic film over small repairs allows wax free gelcoat/resin to cure hard. Epoxy resins do NOT contain wax and do not need it! But, poor quality epoxies do "blush" - this is a wax-like material that forms on the surface - It is not wax, but is formed by a reaction between amines in the hardener and water and carbon dioxide in the air to form an amine carbonate. This is not a problem when laminating, but if the epoxy is allowed to fully cure, this product must be scrubbed or sanded off before applying more epoxy or paint. "Wayne.B" wrote in message ... On 24 Aug 2006 21:24:02 -0500, Dave wrote: Epoxies must be sealed off from air exposure in order to cure. That is not true, you are thinking of polyester resin, not epoxy. They are not the same. |
#23
posted to rec.boats.cruising
|
|||
|
|||
Getting to the bottom of it... (Ablative question)
Which of the two types is West 105? Can one just varnish over a non-waxed epoxy to allow it to cure? Thanks, Chris Dave wrote: On Thu, 24 Aug 2006 22:04:54 -0400, DSK said: I wonder if the problem was amine blush. This is a waxy film that develops across the surface of most epoxies as they cure. Actually, it isn't something that just happens. Epoxies must be sealed off from air exposure in order to cure. That's what the wax does. You can also buy epoxies that don't have the wax, and don't have it specifically so that additional layers can be added before the final cure. To cure these you have to either spray with wax coat, or cover the surface of the epoxy with an airtight wrap. |
#24
posted to rec.boats.cruising
|
|||
|
|||
Getting to the bottom of it... (Ablative question)
|
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
How to Repair the Bottom of a 1,000-lb Boat? | Boat Building |