| Rob Tilton asked that I document the vacuum bagging process.
So I will add the pictures as I go along. These pictures are of the
"H" vacuum distributor I made with 3/4" PVC water pipe. They are dry
fitted into the fittings as you don't care is the joint seal is good.
I drilled holes in all of the pipes every few inches so there is a hole
about every 90 degrees. This distributor made a big difference in the
vacuum I was able to draw. The pipe stub sticking up is what I attach
the vacuum pump to. |
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| Making a new vacuum bag. I bought 6mil plastic from
Home Depo. It comes in a 20' x 100' size. For my HC, I can make
4 vacuum bags with it. I cut it in 4ths and then seal the two ends
with Liquid Nails construction adhesive. Then I cover the edges with
duct tape. It works pretty well. Picture is kind of dark but you get
the idea. (I generally work at night so many pictures are kind of
dark...) |
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| I purchased a bunch of blankets at the Salvation Army to use
as breather material. This helps the airflow inside the bag and the
blankets absorb the excess epoxy that comes through the release ply. I
purchased the release ply from Fiberlay in FL. It comes in two styles:
a perforated blue film #181 that gives a generally slick surface and a weave
#182 that gives a texture for painting or adding additional layers.
The #182 seems to remove more epoxy but is much harder to remove when you
are done. It takes a lot of tugging. I prefer the #182.
You put the fiberglass down like normal wetting it out. Then the
release ply is put over all the fiberglass. It it better to make the
release ply extend a fair amount over the fiberglass edges to keep any stray
epoxy from sticking the blanket to the HC. After the release ply is
put on, the breather cloth is put over all the release ply. Then the
inside vacuum pipes, if you are using them, and finally the bag is pulled over
the HC and the edges sealed with duct tape. I keep the vacuum on for
12 hrs. |
 release
ply #182 after use. The blanket sticks to the release ply.
Blanket can be used twice - each side. |
| I made a vacuum manifold to hook both the shop vac and the
Gast pump to the "H" vacuum distributor in the bag. The shop vac
removes the bulk of the air and then I can use the Gast to do the deep pull.
The Gast is also much quieter than the shop vac. I had to adjust the
Gast to keep the force about 4psi. The force measured 390lbs on a
bathroom scale that is 90 sq/in. Once the shop vac has removed most of
the air, I shut the shop vac valve and the Gast continues to pull a vacuum. |
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| Here is the bag at a little over 4psi. The Gast pump
is very quiet. I have to go around the HC and tape over the little
holes that develop with duct tape but it works pretty well. |
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release
ply #182 after use. The blanket sticks to the release ply.
Blanket can be used twice - each side.
