# how much weldon to use when bonding acrylics



## im_a_clownfish (Sep 19, 2005)

Hi all,

I am making a refugium and was wondering how much weldon to use when bonding acrylics.

Do I have to soak the two surfaces to be bonded, or as long as I put a bit of solvent on each surface to be bonded is that enough? Not sure how much it takes to make a strong seal. I'm using #4, will also caulk the seams (inside and out) with #16 as well.

What do you think? I dont want it to leak or fall apart....but it is only a 10 gallon fuge....


Thanks so much!


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## vvolfe1 (Oct 9, 2006)

from what I have read you only need enough to cover the joint. Anymore is a waste. after that rund some of the 16 on the insides of the joint to make sure it is water tight. Silicon on the other hand is kinda pointless on acrylics.
It just will not stick well enough to for it to be of any use.


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## im_a_clownfish (Sep 19, 2005)

Thanks so much!

Is the #16 toxic? I will caulk the inside joints of the tank with it, but do I need to cover it in silicone so it doesnt pollute the water?

Or is it inert when it dries?


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## harif87 (Jun 5, 2006)

Ive heard testemonials that the more you put the weaker joint youll get. I dont use weld on so much so i dont know from direct experience. But i would say make to sure not to use too much. Silicone isnt totally pointless on acrylic, you could use it to secure the baffles, just dont use it as the primary adhesive for the joints.


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## leveldrummer (May 27, 2005)

silicone wont stick, you wanna use the pin method and let the weldon wick into the joints, hold on... its really hard to explain. let me find the link.


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## leveldrummer (May 27, 2005)

ok clownfish, you need to get an applicator for the weldon, dont just paint it on. go to this site.

http://www.melevsreef.com/acrylics/sumps/chvy/chvy_sump.html

that will help alot, browse around and get ideas about everything. one thing he doesnt mention, is after your done, if you have a seam that still leaks, you can actually get a bunch of your shavings. set the tank at a 45 degree angle, pile the savings in the seam like this










and soak it down with the weldon, the shavings will melt and bond to the acrylic leaving an ugly seam, but it will be water tight. i just did that to my sump. and be careful if you do that, after the shavings dry, they can be very very sharp, so dont run your finger across them to smooth it like silicone, just let it do its thing. good luck. and shoot me a pm if you have any other q?s im going through the same thing right now.


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