Author Topic: Use of the heat gun, blow torch  (Read 18622 times)

Offline narvik

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Use of the heat gun, blow torch
« on: November 02, 2012, 03:07:45 PM »
Hei,
I am allways thinking ahead. How exactly do i use my heat gun or blow torch when there are "bubbles" or similar impurities in the epoxy or laminate.
I could find out by reading Renn`s book once again, but I assume that there is lots of useful and updated advice available.
How: Temperature setting when using an electric heat gun - When: how far into the curing process of the epoxy - Where: what kind of "Bubbles" or other problems can I fix????

Could anybody please give me an "easy to swallow bomb proof" user manual.
Sorry, but I have never done something similar before. Tried myself on a test piece from scrap material, no pleasant result. The "bubble" got soft and could be pressed down, but the epoxy still did not bind to the underlying ply. I just got some kind of flatter but bigger "bubble".

Any advice?
Thank you
Peter

Offline NSchlee

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Re: Use of the heat gun, blow torch
« Reply #1 on: November 02, 2012, 03:23:24 PM »
I've only used a lit propane torch passed approx. 3-4" over resin to help "pop" air bubbles, if you got bubbles under the glass you'll more than likely need to cut out the bubble and reglass the affected area.

Neal
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Offline jim shula

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Re: Use of the heat gun, blow torch
« Reply #2 on: November 02, 2012, 08:37:11 PM »
I've never used a heat gun or blow torch to get rid of air bubbles because 1) I never get bubbles in my lay-ups, and 2) I'm deathly afraid of open flames anywhere in the shop.

adam_kondrashoff

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Re: Use of the heat gun, blow torch
« Reply #3 on: November 03, 2012, 08:49:45 AM »
You need to practice wetting out fiberglass cloth with epoxy.  Once you figure it out you will seldom, or never need a heat gun or blow torch to get rid of bubbles.  Try wetting out fiberglass at different temperatures, I found that it wets out best, when the ambient air temperature is warm, 70 degrees +.  Air temperature affects epoxy performance most, if you do your work in a warm environment, you will have success.

Offline NSchlee

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Re: Use of the heat gun, blow torch
« Reply #4 on: November 03, 2012, 09:08:32 AM »
it's always best to glass as Adam says, when the temp has reached it's peak for the day, this pretty much eliminates out gassing of the material.

Neal
"The problem with socialism is that you eventually run out of other people's money" - Margaret Thatcher

Offline Dave Wright

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Re: Use of the heat gun, blow torch
« Reply #5 on: November 03, 2012, 09:09:03 AM »
The propane torch can remove the bubbles in the resin, but if you overheat you can create even more bubbles that come up from the wood surface below the resin.  I'd rather live with a few bubbles than mess with the torch, potential problems, and the additonal vapors coming up from the process. But, I imagine some guys are very good with this technique and get excellent results.

Offline jerry bark

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Re: Use of the heat gun, blow torch
« Reply #6 on: November 03, 2012, 01:21:40 PM »

How: Temperature setting when using an electric heat gun -

no idea, never used one.

When: how far into the curing process of the epoxy -


as soon as the epoxy is laid up: in other words right away

Where: what kind of "Bubbles" or other problems can I fix????

little tiny air bubble in the epoxy that have floated to the surface. If the epoxy is not still runny you are doing more harm than good by giving it the heat.

if you have glass cloth that is "bubbled" up so that it is no longer in contact with the wood then you have a lay-up problem to resolve. bubbles like this are really a case of the glass is not laying well on the surface, so there is some wrinkle or tension or something in the lay up. for these wait for the epoxy to cure, cut the bubble out and lay up a patch of glass cloth in the hole with some overlap.

If you are going to paint your boat there is really no reason to worry about the tiny air bubbles since you will paint over them all in the end so I would not bother to hit them with a heat gun.

cheers,
Jerry
Tolman Widebody Skiff built in 2011

Sturgis, Michigan

adam_kondrashoff

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Re: Use of the heat gun, blow torch
« Reply #7 on: November 03, 2012, 02:41:12 PM »
Jerry is also correct.  Uneven surface, splinters, and especially sharp corners, will all cause the fiberglass cloth, to lose contact with the substrate.  If that is the case, then your problem is mechanical, not thermal, and no amount of heat will remove these bubbles. 

Offline kiwi les

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Re: Use of the heat gun, blow torch
« Reply #8 on: November 10, 2012, 08:30:41 AM »
If you are getting bubbles in your lay up, then it could be that your timber is very porous and is what they call gassing out. The best and only cure is to coat the timber first to seal it, sand lightly after it has cured then glass over. It could also mean that you are not glassing properly, search out the manual by the "gougone brothers" for west system. I do have a copy of there manual if you can't find it. give me your email address and I will send it to you. Invest in some rollers, I am not talking about foam, but lay up rollers, ie about 18mm usually plastic but maybe metal that have a thread on them with a handle which goes through the centre of the roller. This will break the bubbles as they appear when you roll out.
Some say it is best to wet out the timber first then lay the glass over, but that is a pain in the ass, as you always have problems with cloth placement because it sticks up when you want to move it. Best to lay the cloth down first, pin/tape it so it doesn't move, then resin through using a squeegee. Some use a foam or cloth roller but they can create bubbles. I only use one or a brush when I have no other option. vertical faces can be done with a little practice as well just pour a puddle on then spread out.
Any problems give me a holler.

Kiwi les
ps New job permanant nights 4 on 4 off

Offline David Nolan

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Re: Use of the heat gun, blow torch
« Reply #9 on: November 26, 2012, 02:19:25 PM »


We were laughing too
Hard.     Later on we used this technique for applying gentle heat to
Large areas

Offline Surfrat81

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Re: Use of the heat gun, blow torch
« Reply #10 on: February 19, 2018, 04:21:35 PM »


We were laughing too
Hard.     Later on we used this technique for applying gentle heat to
Large areas
You're a fkn riot!

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