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Getting Lots of Bumps/Bubbles in Poly

  • Posts: 486

colin replied the topic: Getting Lots of Bumps/Bubbles in Poly

Thanks Doug, appreciate you getting back to me on this ... it now eliminates one more thing off the list. I am still doing some checking, if I find out something concrete I will post it here ...

Colin
#7
  • Posts: 269

Derek replied the topic: Getting Lots of Bumps/Bubbles in Poly

Hi Chaplain Doug.

I have been really busy in the shop for the last couple of weeks so I just read through the posts. I have two points that may assist you if you experience some of the troubles you were faced with.
I think you were using the spray can version of the poly acrylic..... if so one issue I have experienced was the spray pattern of the acrylic was spotty while making a pass over a large picture frame I was finishing. I had a few bubbles but they leveled themselves out. When I was preparing to spray the next coat, I grabbed my chair and really spent a few minutes giving that can a very thorough shaking. This eliminated the issue with the spotty pattern.
To address the bubbles you had after laying down the coat of acrylic, I always have a propane torch handy and after spraying a project you can fire up the torch and quickly sweep the flame back and forth over the bubble and they will pop and self level. The trick with this is to fan the trouble area as quickly as you can and keep the flame about 8 to 10 inches away from the the item and remove the heat as soon as the bubble pops. I have used this for many years on large items that I spray finish and this technique works on Epoxy finishes as well. Try this out on some scrap boards to get a feel for this and be careful not to dwell on an area and burn the finish. I hope this will be of some help in the future.

Derek
#8
  • Posts: 40

chaplaindoug replied the topic: Getting Lots of Bumps/Bubbles in Poly

I first applied two coats of water-based poly from aerosol. I did not get bubbles in those coats. It was when I began brushing on water-based poly from a can that the bubble appeared in every coat thereafter. Will the propane trick be okay on brush on? The flame should be parallel to the surface and 8-10 inches away?
#9
  • Posts: 486

colin replied the topic: Getting Lots of Bumps/Bubbles in Poly

Just a word of caution to all ... I know this thread is about water-based finishes, I just want to make the clear to everyone.

Derek's mention of using the torch to help relieve bubbles does work well, but just make sure of what you are flaming. Read the Label, some aerosol sprays are HIGHLY flammable, you could end up with more than bubbles on your finish by trying this with the wrong product.
#10
  • Posts: 269

Derek replied the topic: Getting Lots of Bumps/Bubbles in Poly

Good catch Colin. I had that thought while I was putting this together but lost the point somewhere along the way. :pinch: My bad.

Chaplain Doug, yes parallel and 8 to 10 inches away as a start. Practice on some scrap first and sweep back and forth very quickly and watch the effect on the finish. What you are trying to achieve is to heat the air inside the bubble and cause it to expand to the point where it breaks. You will see the heat from the torch sweep across the finish and as soon as the bubble breaks remove the heat immediately.
Anytime I am forced to use this method, I always give the surfaces a light sanding after the cure and apply a very thin finishing coat. I never allow the final coat of finish to be one that I had to flame except for a Two Part Epoxy finish which sets up and cures very slowly.
#11

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