polyurethane hardener
#1
01-15-11, 05:28 PM
polyurethane hardener
I have some older cans of polyurethane wood stain that I wanted to see if I can add something to the can to make the remaining polyurethane harden in the can so it becomes inert and I can throw it away. I have use something like this for latex paints but haven't been able to find anything for polyurethane.
Anyone have an idea?
Anyone have an idea?
#2
01-15-11, 08:08 PM
RIKIL:
I can't say I really know what "polyurethane wood stain" is, so I'm expecting you either mean polyurethane OR wood stain. However, I do know that years ago, back in the 1970's, they use to sell interior wood stains with both polyurethane and coloured pigments added to them, with everything suspended in mineral spirits. You put that on the wood and the mineral spirits are absorbed by in the wood, and the dyes suspended in the mineral spirits go along for the ride and end up bringing out the wood grain. The polyurethane and coloured pigments are too large to penetrate into the wood and remain on top to provide a coloured "varnish" over the wood. So, the result is that you supposedly both stain and varnish the wood in one operation. If this is what you have, you can treat is a ordinary polyurethane.
Before you ruin the poly, check under "Hazardous Waste" or "Recycling" in your yellow pages phone book to see if there are any hazardous waste drop off depots or paint recycling operations in your area. Oil based polyurethane can be mixed with alkyd paints, and so they should accept your polyurethane.
But, you should check to see whether it's polyurethane you have or a wood stain or a polyurethane wood stain as described in the first paragraph.
I'd take the lid off the can and see if there's any dried skin on top of it. If there's plenty of air space in the can and you find such a skin, then it's an oil based product and you can accelerate it's drying with something called "Japan Dryer", available at most paint stores. Japan Dryer contain salts of cobalt that act as a catalyst in the auto-oxidation process by which all oil based coatings crosslink with oxygen to form solids. So, Japan Dryer should work on drying oils like Tung oil and boiled linseed oil, boiled linseed oil based paints, real varnishes, alkyd paints and polyurethane "varnishes" and hardwood floor finishes.
If it's only an interior wood stain you have, then it won't have any skin on it and won't contain any oil at all. It'll just contain either mineral spirits or alcohol. Japan Dryer won't do anything to mineral spirits or alcohol. In that case, the hazardous waste recycling depots are your best bet since they'll take both mineral spirits and alcohol based products.
I can't say I really know what "polyurethane wood stain" is, so I'm expecting you either mean polyurethane OR wood stain. However, I do know that years ago, back in the 1970's, they use to sell interior wood stains with both polyurethane and coloured pigments added to them, with everything suspended in mineral spirits. You put that on the wood and the mineral spirits are absorbed by in the wood, and the dyes suspended in the mineral spirits go along for the ride and end up bringing out the wood grain. The polyurethane and coloured pigments are too large to penetrate into the wood and remain on top to provide a coloured "varnish" over the wood. So, the result is that you supposedly both stain and varnish the wood in one operation. If this is what you have, you can treat is a ordinary polyurethane.
Before you ruin the poly, check under "Hazardous Waste" or "Recycling" in your yellow pages phone book to see if there are any hazardous waste drop off depots or paint recycling operations in your area. Oil based polyurethane can be mixed with alkyd paints, and so they should accept your polyurethane.
But, you should check to see whether it's polyurethane you have or a wood stain or a polyurethane wood stain as described in the first paragraph.
I'd take the lid off the can and see if there's any dried skin on top of it. If there's plenty of air space in the can and you find such a skin, then it's an oil based product and you can accelerate it's drying with something called "Japan Dryer", available at most paint stores. Japan Dryer contain salts of cobalt that act as a catalyst in the auto-oxidation process by which all oil based coatings crosslink with oxygen to form solids. So, Japan Dryer should work on drying oils like Tung oil and boiled linseed oil, boiled linseed oil based paints, real varnishes, alkyd paints and polyurethane "varnishes" and hardwood floor finishes.
If it's only an interior wood stain you have, then it won't have any skin on it and won't contain any oil at all. It'll just contain either mineral spirits or alcohol. Japan Dryer won't do anything to mineral spirits or alcohol. In that case, the hazardous waste recycling depots are your best bet since they'll take both mineral spirits and alcohol based products.
#4
01-16-11, 09:47 PM
Normally, Japan Dryer is meant to accelerate the drying time of oil based coatings, but you want to actually solidify the polyurethane, so you might want to use more of the stuff than is recommended on the container of Japan Dryer. Maybe 3 or 4 times as much.
Also, the Japan Dryer is only a catalyst that promotes the reaction of the unsaturated sites in the oil based coating with oxygen in the air. It won't do any good to add the Japan Dryer if you don't introduce oxygen into the paint. One way I'm thinking you could do that would be to open the can, stir the paint, close the can, shake the can vigorously, then let the can sit for half an hour, open the can, stir the paint, close the can, shake the paint vigorously, let the can sit for half an hour, and keep going.
Oil based coatings absorb oxygen molecules from the air. Without oxygen being absorbed into the wet paint, it won't cure no matter how much catalyst is inside it. So, not only do you have to add the catalyst to promote the reaction with oxygen, you have to ensure oxygen gets absorbed into all of the paint for it to react at the unsaturated sites. Otherwise, it'll just form a skin on top, and the paint under that skin will still be a liquid.
Also, the Japan Dryer is only a catalyst that promotes the reaction of the unsaturated sites in the oil based coating with oxygen in the air. It won't do any good to add the Japan Dryer if you don't introduce oxygen into the paint. One way I'm thinking you could do that would be to open the can, stir the paint, close the can, shake the can vigorously, then let the can sit for half an hour, open the can, stir the paint, close the can, shake the paint vigorously, let the can sit for half an hour, and keep going.
Oil based coatings absorb oxygen molecules from the air. Without oxygen being absorbed into the wet paint, it won't cure no matter how much catalyst is inside it. So, not only do you have to add the catalyst to promote the reaction with oxygen, you have to ensure oxygen gets absorbed into all of the paint for it to react at the unsaturated sites. Otherwise, it'll just form a skin on top, and the paint under that skin will still be a liquid.
