# ??hot wire styrofoam cutter question??



## Saleen281 (Feb 22, 2012)

has anyone used these to cut styro for a diy 3d background? is it safe for the fish once in the tank? the reason i ask is because i made a 3d background using a hot wire cutter a couple months ago for a 20 gallon long . i also covered it with drylok and let it cure over night. im not sure what i did wrong but my fish soon started the die after a couple weeks in the tank. btw the tank was already established. also i noticed that the styrofoam started to shrink has anyone ever heard of this happening? the only materials i used where styro, hot wire cutter and drylock and cement color. :-? :-? so i took the background out and now my fish are fine... weird :-?


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## theoryguru (Oct 11, 2011)

I'm not familiar with a 'hot wire cutter' although I assume the fumes would deter me from using one.
What kind of styro did you use ? - closed cell (pink/blue board) or open cell (white styro)


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## Saleen281 (Feb 22, 2012)

open cell white one .


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## Steve C (Oct 9, 2011)

Some people do use hot wire to cut the foam, personally I like to use knives but the how wire does work for some. Most likely it was something else that caused the fish death.

How long between applying drylok and adding fish was it?

How long between siliconing the BG into the tank and adding fish?

Which silicone did you use?


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## Saleen281 (Feb 22, 2012)

i beleive it was like 24 hours between applying drylok and adding fish
and another 24 hours between siliconing the BG into the tank and adding fish
i used GE1 Silicone.


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## Saleen281 (Feb 22, 2012)

but what would have caused the shrinkage?


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## Frank H (Mar 11, 2013)

Im thinking you should have waited longer to let the drylok cure before adding it to the tank. Also same with the silicone. 24 hours is enough for a full cure of a thin application, but if its thicker than 1/4 then dry time multiplies. *** used GE1 and GE2 silicone and always smell traces of it after 48 hours. I always let it cure till the smell is gone. Usually 3 days up to a week if used thick.

Dont kno what would make styrophome shrink. thats weird.


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## Steve C (Oct 9, 2011)

Saleen281 said:


> i beleive it was like 24 hours between applying drylok and adding fish
> and another 24 hours between siliconing the BG into the tank and adding fish
> i used GE1 Silicone.


I'm not quite following ya....24hrs between drylocking and adding fish, then another 24 between siliconing and adding fish....those two statements are conflicting each other unless I'm missing something, or maybe you just typed it wrong?

At any rate though, I would say the problem is that you did not wait long enough. You need to wait at the very least 3-4 days after it is done and in the tank and all leeched out. The silicone is still off gassing after only 1-2 days. When I did mine I let it sit for a week after I siliconed it into the tank so it would off gas. Then I filled and drained the tank twice just to be on the safe side. Then after that I fishless cycled for 37 days till it was ready for fish. If you plan to do a BG again then wait at least a minimum of 3-4 days (a week is best as Frank mentioned above) before even putting water in it.

As to the shrinking....I have no idea on that one, that sounds odd. Did you apply the drylok directly to the bare foam? Didn't put anything (any paint) on the foam first right?


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## Saleen281 (Feb 22, 2012)

Ur right Steve. I was in a rush when I was typing. But about the bg I'm sure I didn't wait long enough for everything to cure I think I was just too anxious to set everything up that it all fell apart. Ohh and about the shrinkage I have no clue why that happend when I painted the whole thing I mixed the drylok with the quickrete cement paint siliconed the whole thing but after a few weeks I realized my syno catfish were disappearing. Come to find out the where bidding underneath the bg that had shrunk the bottom of te background was shrinking up if that makes sense lol


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## Steve C (Oct 9, 2011)

Yeah it can be hard after doing a BG to not want to get it in and get fish in it right away  Just gotta make sure to wait a bit on the next one it sounds like. I wish I could say why it shrank up like that but I have honestly never even heard of one doing that so I'm a bit lost as to what to tell you there.


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## DanniGirl (Jan 25, 2007)

Great advice from *Steve C* and *Frank H*.

I've used a wire cutter for various projects with no ill effects. Like Steve, I prefer to opt without it. However, I do burn small portions of the foam to give it a smooth edge. A wire cutter just burns the Styrofoam, it doesn't compromise the integrity of the foam.

It was mentioned that open cell styrofoam was used, but what kind? Some insulation contains insecticides, such as Insulfoam.

Open Celled Styrofoam will shrink overtime but usually that takes years. Even then, the measurable amount is minuscule, about an 1/8". 
If it's sufficiently coated with a sealer, it will last a while.

The first coat of Drylok (depending on the thickness) should be allowed to dry over a 24-hour period. However, if the Drylok coat is thin (dry brush consistency) then it will be fine within a few hours. If it was the Drylok, you would have seen deaths within hours/days.

I agree with *Steve C* and *Frank H*, it may have been the silicone. Both gave good advice in regards to the silicone.


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