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How to stop bubbles is the top resin layer?

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plummet
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How to stop bubbles is the top resin layer?

Postby plummet » Fri Sep 30, 2016 8:00 pm

Ok men. I know it's been discussed here before but I can't find it. What's your tips to stop bubbles in the top coat resin layer that you put on after all the vac bagging ect is complete?
image.jpeg

plummet
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Re: How to stop bubbles is the top resin layer?

Postby plummet » Fri Sep 30, 2016 8:07 pm

Here's some techniques i'm trying. Warm the resin in the pot with a heat gun.
vacuum degass the resin first. ( epic fail, I imploded my plastic vacuum chamber I made from a tupaware container.... doh)
spread resin with finger (have a latex glove on)not brush.
mist spray offending bubbles with acetone. (this probably has the best result)
heat work with heat gun prior to wet up so resin flows nicely.
Ensure a thick enough coat for popped bubbles to fill in. and for sanding later.

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Re: How to stop bubbles is the top resin layer?

Postby BWD » Fri Sep 30, 2016 8:38 pm

The common thread in bubbles and fish eyes due to dust, oil, other contamination as well as heterogeneous substrates of other kinds, is the surface electrochemistry is not as agreeable to the resin, so it doesn't want to wet it and instead makes "fish eyes" or holds bubble instead of releasing them.
What can you do about it?
1. Cleanliness - traces of dirt and contamination are the enemy. Good luck with that! Cleanliness may be next to Godliness but i am definitely a mortal in the workshop...
2. Warm the resin and the substrate. You can use a water bath or microwave the resin (NOT the hardener!!!) a FEW seconds, aim for 30-33 C.
3. Pre-coat: mix a small amount of resin and squeegee it onto the substrate, then squeegee it right off leaving a very thin smear or film of resin. Then coat with normal thicker hot coat. The squeegee can force some resin to stick to contaminated or dirty surfaces where it would otherwise refuse to do so. Once it is resin trying to stick to resin, it works better.
4. Thin slightly with 91% isopropanol, acetone or xylene (xylene flashes off fastest). Only 2-3% by volume is recommended.
5. Use a different brush or roller if the application method is contributing to the problem.
6. Mind the humidity, too much is not good.
7. Coat in falling temperatures so any bubbles or air from a porous substrate will shrink rather than expand.
8. Use a gloved finger to gently rub the resin onto any spot it won't stick.

FWIW that strut looks pretty fine, I would just go after the imperfections near the edges after cure if it was me. But I'm a bit lazy.

plummet
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Re: How to stop bubbles is the top resin layer?

Postby plummet » Fri Sep 30, 2016 9:22 pm

Excellent suggestions BWD. keep em coming men.

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Re: How to stop bubbles is the top resin layer?

Postby Blackrat » Fri Sep 30, 2016 10:27 pm

are you talking about bubbles or pinholes ?

bubbles pop instantly with an open flame torch moved over the area very quick

pinholes are just a pain

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Re: How to stop bubbles is the top resin layer?

Postby plummet » Sat Oct 01, 2016 12:25 am

Blackrat wrote:are you talking about bubbles or pinholes ?

bubbles pop instantly with an open flame torch moved over the area very quick

pinholes are just a pain
Both I guess.

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Re: How to stop bubbles is the top resin layer?

Postby rynhardt » Sat Oct 01, 2016 6:28 am

Heat gun or alcohol mister. Use a hair salon mister bottle.

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Re: How to stop bubbles is the top resin layer?

Postby TomW » Sat Oct 01, 2016 6:34 pm

1. Clean the part with dna, blow off with compressed air( have a filter on your air supply) .
2. Do not touch with bare hands. Use disposable gloves.
3. Use brush on, squeegee off method with small amount of epoxy
4. Brush has to be de- contaminated with tape.
5. Brush on epoxy, let it sit 5 min, hit it with flame or hot airgun.
6. Your area has to be free of dust and air current.


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