acrylic bowing/bending

[4tangs]

So I made a pair of algae scrubbers from the plans provided by santa monica sm100. After a short time the lid is bowing badly. Any idea why this would happen? Made from two pieces of 1/4" acrylic glued together....

[4tangs]

Anybody ever run into anything like this?

[hebygb]

a picture is worth a thousand words since there are many designs for algae scrubbers. My hunch is that because acrylic absorbs moisture, that you are experiencing natural behavior of acrylic. This is the same affect that acrylic covers (for access holes) are subjected to.

[4tangs]

Ill work on the picture. So if its because of moisture how do you stop it from happening?

[jimmyj7090]

Yup, water being absorbed. It warps because the wet side takes up more than the dry side.

If possible, flip the covers over an they should flatten out at least a little.

If you want aovid this happening in the future, use glass for the covers.

[SimonSKL]

Can it be from the heat of the light?

[JohnnyB in SD]

Heat from the lamps could warp acrylic.
Posting pics might be helpful to get suggestions or a determination.

[jimmyj7090]

Could be, but water absorbtion is more likely.

If it's heat the acrylic should bow down away from the light/heat. If it's water it should bow up away from the water.

[jimmyj7090]

Oops, double post.

[Drag Racer]

Where did you get the acrylic from?

[4tangs]

I got the acrylic from rideoutplastics supplied the acrylic.
Im trying to figure out how to ad a picture now.

[4tangs]

https://lh4.googleusercontent.com/-hn95M4pFvck/T0vmJZLt5cI/AAAAAAAAA-I/eI735PFKKh8/s963/2012-02-27_13-18-22_536.jpg

[4tangs]

https://lh5.googleusercontent.com/-vdyOXFDjY64/T0vmLo-lFGI/AAAAAAAAA-Q/RrJL4lf_ZhY/s963/2012-02-27_13-19-00_766.jpg

As you can see it is two pieces of acrylic glued together to make a lid.

[4tangs]

https://lh5.googleusercontent.com/-vdyOXFDjY64/T0vmLo-lFGI/AAAAAAAAA-Q/RrJL4lf_ZhY/s963/2012-02-27_13-19-00_766.jpg

As you can see it is two pieces of acrylic glued together to make a lid.


Heres a picture of the whole unit
https://lh3.googleusercontent.com/-UoOqehaevJM/TvqtZIJNHBI/AAAAAAAAAbI/PwP6ggG2N5o/s543/2011-12-27_22-47-07_262.jpg

[Acrylics]

just water absorption..nothing less, nothing more.. Heat is relatively meaningless in this case. Wet side will absorb water so will grow and "cup" - as such, the wet side will *always* become convex.

Add a second "smaller" piece to the other side if you wish and make it reversible, use glass, or use Lexan or similar polycarbonate to eliminate this from happening in the future.

James