# polyurethane safe



## Polarshrey

Is polyurethane foam safe in an aquarium


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## lbacha

Yes it is, it's what great stuff is made of and that has been used for years to make fake rocks and backgrounds, I would make sure no other chemicals are present that might be toxic but polyurethane is fine one cured. If you are talking about polyurethane as in the clear sealant on wood make sure you use a marine/waterproof version of it but I've sealed a lot of wooden tanks with it in the past and it's used on the hulls of wooden boats.

Len


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## GraphicGr8s

lbacha said:


> Yes it is, it's what great stuff is made of and that has been used for years to make fake rocks and backgrounds, I would make sure no other chemicals are present that might be toxic but polyurethane is fine one cured. If you are talking about polyurethane as in the clear sealant on wood make sure you use a marine/waterproof version of it but I've sealed a lot of wooden tanks with it in the past and it's used on the hulls of wooden boats.
> 
> Len


Polyurethane is actually a plastic and is waterproof. The marine version adds UV inhibitors to protect from the effects of the sun. Spar varnish forms a more flexible finish since it's original use was on a spar on a boat which flexes.

Poly, when fully cured is a food safe finish.


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## Steve001

Polarshrey said:


> Is polyurethane foam safe in an aquarium





lbacha said:


> Yes it is, it's what great stuff is made of and that has been used for years to make fake rocks and backgrounds, I would make sure no other chemicals are present that might be toxic but polyurethane is fine one cured. If you are talking about polyurethane as in the clear sealant on wood make sure you use a marine/waterproof version of it but I've sealed a lot of wooden tanks with it in the past and it's used on the hulls of wooden boats.
> 
> Len





GraphicGr8s said:


> Polyurethane is actually a plastic and is waterproof. The marine version adds UV inhibitors to protect from the effects of the sun. Spar varnish forms a more flexible finish since it's original use was on a spar on a boat which flexes.
> 
> Poly, when fully cured is a food safe finish.



It should be noted that there are different grades of polyurethanes and polyurethane foams. They are graded from industrial which may not be safe to medical grade which would be safe. It is wise to check beforehand the safety of such a product when adding it to a small volume of water such as an aquarium.


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## GraphicGr8s

Guess I should have said the polys used in furniture finishing are food safe when fully cured. 



> TITLE 21--FOOD AND DRUGS
> CHAPTER I--FOOD AND DRUG ADMINISTRATION
> DEPARTMENT OF HEALTH AND HUMAN SERVICES
> SUBCHAPTER B--FOOD FOR HUMAN CONSUMPTION (CONTINUED)
> 
> PART 175 -- INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS
> 
> Subpart C--Substances for Use as Components of Coatings
> Sec. 175.300 Resinous and polymeric coatings.
> 
> Resinous and polymeric coatings may be safely used as the food-contact surface of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, in accordance with the following prescribed conditions:
> 
> (a) The coating is applied as a continuous film or enamel over a metal substrate, or the coating is intended for repeated food-contact use and is applied to any suitable substrate as a continuous film or enamel that serves as a functional barrier between the food and the substrate. The coating is characterized by one or more of the following descriptions:
> 
> (1) Coatings cured by oxidation.
> 
> (2) Coatings cured by polymerization, condensation, and/or cross-linking without oxidation.
> 
> (3) Coatings prepared from prepolymerized substances.
> 
> (b) The coatings are formulated from optional substances that may include:
> 
> (1) Substances generally recognized as safe in food.
> 
> (2) Substances the use of which is permitted by regulations in this part or which are permitted by prior sanction or approval and employed under the specific conditions, if any, of the prior sanction or approval.


http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=175.300

Shellac, which is the excrement from the lac bug is used as a coating on many drugs. Once the alcohol evaporates it's completely safe. It's just not water resistant at all.


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## Polarshrey

So i can use it if it is cured with alcohol, can i use ethyl its the only one i have


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## klaus07

If you are buying off the shelf commercial foam, you have to make sure it doesn't have additives to make it mildew resistent. If it does it will kill your fish and shrimp. Craft stores, like Hobby Lobby or Michaels has foam. The hypoallergenic one is safe to use. Id you are crafting your own, then you can control the additives.

In my experience, though more expensive, Poret Foam, is designed for aquariums and safe for fish and shrimp, is worth the cost as its open cell nature is controlled by design for the aquarium. If the foam is too fine and its being used as a filter, it could eventually collapse if it fills with particles.

Klaus


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## Polarshrey

Thanks but the cover just said polyurethane foam.


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