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Author Topic: Strange happenings  (Read 352 times)

ukmike

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Strange happenings
« on: September 07, 2021, 07:35:14 pm »

Hello.


A strange thing has happened to the paint on my Winch but not the Bow Roller.


I've used the same brand for each coat and followed the same procedure after each coat, the winch is made from medium Balsa and the Bow roller American White


 Oak. The paint is Acrylic.


Each cote was left for well over 24 hours before sanding and painting on both items before re sanding and adding another coat, 4 coats in all went very well.


Today, following another 24 hours plus I noticed tiny bubbles had appeared on part of the winch but not the roller, as the day wore on they increased in numbers and


size. I determined that it must be gas of some sort so I sanded through each coat to find out where the bubbles emanated from, they were present down to the


bare wood. I have removed all of the paint using Gun Wash and starting from scratch but would like some ideas regarding the possible cause so that it won't happen


again


The photos' show the no bubbles at first, then appearing early this morning, still no problems with the roller.


Mike.


 


 
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JimG

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Re: Strange happenings
« Reply #1 on: September 08, 2021, 12:36:02 pm »

Balsa has a very open grain which after drying will be full of air replacing the original water in the wood. I tend to find that  with some acrylics the solvent will soften the existing paints allowing it to soak into the wood grain and allowing air in the grain to escape. Balsa needs to be properly sealed before painting while other woods with a tighter grain can be painted directly. I always seal balsa with finishing epoxy with some microballoons added which both hardens the surface of the wood and gives a smooth surface after sanding, ready for the paint.
Jim
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ukmike

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Re: Strange happenings
« Reply #2 on: September 08, 2021, 10:25:55 pm »

Hi Jim.


Thanks for the explanation, it makes complete sense and I suppose the very high temps. in the last few days haven't helped,32 degrees in my shed.


I very rarely use Balsa and never had the need to paint it, but, I did apply a sealer but obviously it wasn't good enough.


Mike.


 
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RST

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Re: Strange happenings
« Reply #3 on: September 08, 2021, 11:34:08 pm »

"I did apply a sealer". There you go, that's another myriad of questions and why I doubt I'm the only one impressed with the finish without knowing what the prep and paint was.  It looked great so far -what was wrong with just spot filling the few holes and re-painting?  No big problem?  Sorry, not to appear argumentative but it seems no problem here?


Rich
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ukmike

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Re: Strange happenings
« Reply #4 on: September 08, 2021, 11:54:32 pm »

"I did apply a sealer". There you go, that's another myriad of questions and why I doubt I'm the only one impressed with the finish without knowing what the prep and paint was.  It looked great so far -what was wrong with just spot filling the few holes and re-painting?  No big problem?  Sorry, not to appear argumentative but it seems no problem here?


Hi Rich.


As I said in the opening post the bubbles continued to appear and covered about 25% of the whole piece. It would have been a thankless task to correct as I didn't know when it would stop. That's why I removed all of the paint back to the wood. I have since thrown it away(don't like Balsa anyway) and made another one from European Lime which shows no sign of bubbling, at least after the first 2 coats
Fingers crossed all should be well now.


Mike.
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ukmike

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Re: Strange happenings
« Reply #5 on: Yesterday at 03:04:10 pm »

Mk.2 Winch and Bow Roller, Lime Wood this time, finished in satin black


No problems.


Mike.
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