Talk Composites - The Forum for Advanced Composites

Haze turns to scales

http://www.talkcomposites.com/Topic31915.aspx

By Randy Mugford - 2/4/2019 3:40:44 PM

Hello, I am casting my projects upside down on a smooth plastic, almost glass surface. I cast this way as I place my furniture pieces in the resin on my second or third pour ( curved wood). I notice a soon as I pour my first coat, a haze like film appears on the surface, almost seems to thicken instantly. It is only obvious at an angle initially. As the project cures, over a period of a few days this haze goes scally/off white and noticeable looking through the resin once removed from the mold and flipped over. As I have curved wood in the resin protruding out is is impossible to sand out/remove. How do I avoid this initial haze? I have attached two images. the close up is the image looking through the top, where you can see the white scales.
By Randy Mugford - 2/7/2019 11:16:19 AM

 
Warren (Staff) - 2/7/2019 11:08:40 AM
The only time I have seen a scummy film like that on GlassCast has been when the temperature has dropped or the humidity was a bit high either generally or locally.  We found  that if you leave it, the exotherm tended to drive out the moisture with it going clear again.  However when we tried to mix it in or scrape it, it just picked up more resin as you did so making it look worse.

Thanks again. After scraping it off ( took an hour) it was clear and fine. Leaving it on the last pour creates a blush when it dries that is impossible to get rid of, and worsens over time. I do live by the ocean, in a humid environment, but heat the drying room with electric heater, and kept the moisture at 40% in the room. Urgh! Thanks for you knowledge!. i will send an image of the finished project. Just not waiting for the the resin to get to a stage where I can manipulate it by have and ad texture.