CA Accelerant on Polyurethane

[pat miller]

I have a piece finished with polyurethane to which I added some decorative thread. I used CA glue to harden/finish the thread and shot it with a bit of accelerant to quicken the set up and hold it in place. It appears that the accelerant has softened the finish and it does not want to firm back up still remaining tacky- probably a week has gone by. It's not something that I can remove the finish and reapply. Any idea of a way to firm the finish back up? Will it possibly return to normal in time?
Thanks for your suggestions..

 

[Bill Boehme]

Has it also cause the finish to look slightly hazy? I have seen a slightly hazy appearance on lacquer caused by the pump spray accelerator which I think is mainly acetone, however, the lacquer finish didn't stay soft. I think think that the main ingredient in the aerosol accelerator is nitro methane which might be the reason for the gummy finish. I spilled nitro methane in a toolbox and it turned some plastic screwdriver handles gummy and they never did harden.

 

[Mark Mandell]

Has it also cause the finish to look slightly hazy? I have seen a slightly hazy appearance on lacquer caused by the pump spray accelerator which I think is mainly acetone, however, the lacquer finish didn't stay soft. I think think that the main ingredient in the aerosol accelerator is nitro methane which might be the reason for the gummy finish. I spilled nitro methane in a toolbox and it turned some plastic screwdriver handles gummy and they never did harden.

"Nitro" is used as a debonder for CA rather than an accelerant. Most accelerators I've used were a mix of isopropyl alcohol and water. The alcohol makes it dry faster and the water is the actual accelerant because it's the primary reactant that makes CA set up. In the OP situation, something applied has broken the poly's long bonds. Since polys cure in one direction, I doubt there is anything that can be done; once the polymers in the finish film are destroyed I would anticipate that the only option is to strip and refinish. I could better understand the situation if the OP actually sprayed nitro on the piece as that might attack the finish film, but that's only a guess.

 

[Bill Boehme]

"Nitro" is used as a debonder for CA rather than an accelerant. Most accelerators I've used were a mix of isopropyl alcohol and water. The alcohol makes it dry faster and the water is the actual accelerant because it's the primary reactant that makes CA set up. In the OP situation, something applied has broken the poly's long bonds. Since polys cure in one direction, I doubt there is anything that can be done; once the polymers in the finish film are destroyed I would anticipate that the only option is to strip and refinish. I could better understand the situation if the OP actually sprayed nitro on the piece as that might attack the finish film, but that's only a guess.

This is wandering OT, but I'll have to disagree about the accelerator being water and isopropanol. The typical aerosol accelerator contains acetone, heptane, and N,N-Dimethyl-P-Toluidine (the last ingredient is extremely toxic and carcinogenic. I can smell acetone in the pump spray accelerator from Starbond, but I don't know what else it has. Starbond has a debonder that I was immediately able to tell that it was nothing more than methylene chloride, AKA, paint stripper. Don't ever use the stuff to remove CA from your skin -- it's really nasty stuff. I think that you are right about nitro methane being used as a debonder. I know one of the products had the unmistakable smell of nitro and I probably had it backwards. When I was a kid, model airplane fuel was mostly nitro -- much more than now if I am not mistaken.

Anyway, if polyurethane is cured, it is fairly impervious to CA accelerator. If not cured, I suppose that something in the accelerator is preventing it from crosslinking.

 

[Ian Thorn]

Pat

You haven't said if you cut the thread before or after you sprayed with the poly. Just my thoughts, if the thread had no poly and you applied the CA then used the accelerator you may have been a bit too close and it has had the revers effect I have had that result on a pen. As an aside I don't use the accelerator but use Dettol Disinfectant spray the propellant is Hydrocarbon I would suggest the hydro and moisture dose the accelerating but I may be wrong.

 

[Mark Mandell]

This is wandering OT, but I'll have to disagree about the accelerator being water and isopropanol. The typical aerosol accelerator contains acetone, heptane, and N,N-Dimethyl-P-Toluidine (the last ingredient is extremely toxic and carcinogenic. I can smell acetone in the pump spray accelerator from Starbond, but I don't know what else it has. Starbond has a debonder that I was immediately able to tell that it was nothing more than methylene chloride, AKA, paint stripper. Don't ever use the stuff to remove CA from your skin -- it's really nasty stuff. I think that you are right about nitro methane being used as a debonder. I know one of the products had the unmistakable smell of nitro and I probably had it backwards. When I was a kid, model airplane fuel was mostly nitro -- much more than now if I am not mistaken.

Anyway, if polyurethane is cured, it is fairly impervious to CA accelerator. If not cured, I suppose that something in the accelerator is preventing it from crosslinking.

http://www.google.com/url?sa=t&rct=...5L9Sch3V2P6iUgQkRkUTrUQ&bvm=bv.76943099,d.aWw

http://krayden.com/technical-data-sheet/henk_loctite_7452_tds/

http://www.henkelna.com/msds-search...ds|action=search|country=US|y=24|language=EN|

The model airplane guys use a little water or baking soda.

Seems like there are a number of things to speed the stuff to set. If the OP had the acetone version, that would probably account for the poly getting dissolved.

 

[pat miller]

Thanks all-
I used the Starbond aerosol accelerant that, given my nose test, I'd say is acetone based. We have the piece setting with a small fan blowing on the surface and it appears to be helping. We may save this yet.......

 

[Mark Mandell]

Thanks all-
I used the Starbond aerosol accelerant that, given my nose test, I'd say is acetone based. We have the piece setting with a small fan blowing on the surface and it appears to be helping. We may save this yet.......

Pat,
If you get it to dry, don't rely on the durability of the coating. As far as I could find out, the poly will not "re-polymerize" to a durable coating. You should consider recoating with something like shellac or lacquer. Best way to test is to apply your poly to a board. Allow it to cure for a week or two, then hit it with your acelerator to replicate the present situation. Allow it to dry and then see what you have left as a coating.

 

[Bill Boehme]

..... Most accelerators I've used were a mix of isopropyl alcohol and water. The alcohol makes it dry faster and the water is the actual accelerant because it's the primary reactant that makes CA set up...

You're talking about a home brew accelerator I presume since ordinary rubbing alcohol is 30% water and 70% isopropanol. I also have 91% rubbing alcohol which is much harder to find, but it flashes off almost instantly. I think that the OP was using a commercial product. The best accelerator by far is human skin. Don't ask how I know this ... my lips are sealed. 🙄

In the OP situation, something applied has broken the poly's long bonds. Since polys cure in one direction, I doubt there is anything that can be done; once the polymers in the finish film are destroyed I would anticipate that the only option is to strip and refinish... [/QUOTE]

I was thinking the same thing if something upset the curing before cross linking really got going.