CA glue got yellow after months - any hints how to repair?

[Drazen]

Hopefully somebody has experience and some hints…

 

I have a question concerning the gluing with super-glue (cyanoacrylate). After several months, I was using CA glue, some of my parts (a very important ones and already installed) got yellow with the time. Please see the photos where you can see the problem: before one year right after gluing and now.

 

My questions:

• What do you do against this?
• Is there a procedure to remove the yellow tone?
• How is with the resin/epoxy, same problem or not so strong as with CA?

 

 

Here are few facts about this problem:

• I was thinking it could be a reaction with the shellac, but there are parts without any shellac and still yellowing strong.
• The problem occurred after 6 to 10 months after gluing
• The wood material where it occurred is maple.
• At the same time, I made a ladder out of pear wood. There, I cannot see any yellow effect.
• The water outlets were on the ship and the gratings were in the closed plastic box - same effect of yellowing.
• On some parts, I was using the activator to accelerate CA, and on some not - no difference in effect.
• The glue was CA fluid and also gel - no difference.
• The humidity in my cellar where I work is from 45% in winter up to 70% in summer.

The water outlets are already installed and very difficult to repair. The yellow effect would ruin the impression of the ship significantly. I positioned today a small part near the window to see if sunlight can minimize the effect. I know that the decals on plastic models can get yellow with the time and this can be removed if one leaves the model on the direct sunlight - than it gets white again.

 

Any idea?

 

Thanks in advance.

Drazen

[druxey]

That is such a shame: your work looks lovely otherwise. The glue appears to have wicked into the wood, so I doubt if there is any remedy for the problem other than perhaps trying acetone. This is wicked stuff and should only be used in a well ventilated space, with organic solvent respiratory protection and absolutely no spark or flame in the vicinity.

 

Myself, I would never use CA glue anywhere at all on a quality model. White and yellow glue is good for wood and epoxy for wood/metal joints.

[dgbot]

I agree with Druxey.  Seepage and out gassing.  Acetone may do the trick but make sure you have good ventilation and no sparks.  Also protection for your hands and respiration. Also the stuff is so easy to use that people forget how dangerous and harmful the stuff is.  Our safety inspector made an inspection of our plant and when She saw us using the stuff to clean and prep material for laminating She had a fit. My advice would be to wear some eye protection as well as just one drop and permanently blind you if you get sloppy and splash the stuff.

David B

[Drazen]

I was wondering if any chemical could neutralize the yellow color and keep the bond?

It is quite sure that the CA penetrated into the wood. Also, on the pear wood, there is no effect of yellowing; just on the maple wood – strange.

 

Drazen

[Drazen]

I have forgotten about this topic, but still want to leave the hint as an answer to my own question:  The yellow shade goes away after leaving the model or the part behind the window on the direct sun. It takes several weeks (4-5) till the yellow disappears. Probably, the direct sun exposure (without any window glass in between) will accelerate the process even more. I am just making some tests.

 

The yellow shade does not appear on pear wood, so, better to use pear as building material.

 

Drazen

[keelhauled]

Glad to hear that you found a solution.  Varnish and linseed oil will do the same.  They may turn yellow with age, but can be sun bleached.  The down side is that the UV from the sun which is bleaching these solutions can also destroy many dyes.

best

Marc

[Bob Cleek]

On ‎2‎/‎21‎/‎2015 at 4:42 PM, dgbot said:

 Our safety inspector made an inspection of our plant and when She saw us using the stuff to clean and prep material for laminating She had a fit.

I would have been one of her targets, no doubt. I've used a lot of it over the years, but somewhere along the line I started using white vinegar to wash my hands after getting epoxy all over them instead of using the acetone I had customarily used before. It wasn't a safety issue. The white vinegar was cheaper than the acetone was all. I survived without any ill effects, or so it seems. All things in moderation, though. Lots of ventilation. No solvent-, oil-,  or linseed oil-soaked rags left in the shop. Ever.

 

 

[allanyed]

Drazen,

Sorry but I cannot help myself on this one.  You wrote "The yellow shade does not appear on pear wood, so, better to use pear as building material. " 

This is just my own opinion, but my response is "better not to use CA  as a building material"

Allan

Edited May 29, 2019 by allanyed

[druxey]

I concur with Allan!