what not to do with polyester

[raalst]

I did my first lay-up a few days ago.

The idea is to create a strong shell to protect the foam/gypsum plug
(and as a basis to apply further filler).

As there were concave surfaces and
sharp edges I wanted to fix my glass weave to the hull first,
then apply polyester.

I used white wood glue for this. Turns out that the glass/polyester
mix now detaches from the hull in exactly the spots where glue was used.

that's not what you want....

[anonymous]

I just use 3M 77

I just use 3M 77 lightly over the foam and smooth down my glass just perfect, then I apply the resin.

BTW polyester you need to let sit a few days before snading or you'll clog your sand paper. Wet sanding helps with this is the resin is quite there yet.

That's why I stopped using polyester. Besides the smell it always took longer for the surface to cure or I was doing somethime wrong. But with epoxy 24 hours and she ready to sand.

The 3M 77 works real good and I've done many many hulls and RC jet plugs this way.

steve

[raalst]

thanks steve,

unfortunately I have

thanks steve,

unfortunately I have never seen it over here in the neterlands.
but i'll have a search for it...

[tsenecal]

raalst

thinking outside the box:

I use

raalst

thinking outside the box:

I use 3M 77 as a tack glue to mount photos on mattes.

try looking for a low tack spray adhesive in photo and camera shops or frame stores if you can't find the 3M 77.

[raalst]

thanks Tsenecal ! that is

thanks Tsenecal ! that is a good lead.

I must admit I have seen it once, used by a consultant in a workshop.
so office supply stores are another place to search.

[Guest]

I haven't used the 3M

I haven't used the 3M product, however I think it may be a contact type of adhesive?

Upholsterers use a spray contact adhesive to fix cloth onto foam cushions etc.

You could try a local upholstery shop and ask if they have a can they could sell you.

Andy

[raalst]

found it.

the local bookstore

found it.

the local bookstore had it tucked away somewhere...

thanks for the leads.

[mkeatingss]

A bit off topic

I'm sitting here reading this, and a picture keeps popping into my head.
It's of the salesman's face, when you walk into an office supply or upholstery shop, and say, "I'm building a working model submarine, and I need some help." Or words to that effect.
Probably similar to the look I got, the first time I walked into my local model Railway shop and stated, "I'm building a model sub and need some diesel engines."
Or the poor woman. at the sewing shop. when I asked for the thinnest single strand thread she had. She asked what I needed it for. I just said, "My submarine." I wish I'd thought to bring a camera.
Mike K.

[aeroengineer1]

Mike I have had that

Mike I have had that experience many times even going to the local hobby shop asking for things. I tell them that it is for a model submarine and the get the stupid dog look on their face and then state that they do not sell parts for a model submarine, that all thier stuff is for cars or airplanes. I love it wen I tell them that it is ok, it works in a submarine too.

Adam

[crazy ivan]

I've even had it happen

I've even had it happen trying to buy loose o-rings at the home center. "No, it's not any kind of faucet, it's for my submarine." Sheesh, you would think at least a hardware oriented store would understand such things. No way. I'll have to see how it works at the local marine supply store.

[bigdave]

George, I went to the

George, I went to the Doctor the other day and had an 8-ball shirt on. He looked at the logo and thought it was a BOMB!! Ha!! BD.

[Guest]

Silly sod, how could he

Silly sod, how could he make a mistake like that!

[raalst]

just for completeness,

it seems

just for completeness,

it seems the wood glue was not the mayor cause for the problem.
I pried open a blister and it turned out that the whole glassed area
was still soft. not just where the glue was, but everywhere.
It also detached easily from the gypsum.
I peeled the majority of it off the plug.

so I conclude there must have been a problem with the hardening
process. too little hardener or maybe too low a temperature, who knows.

The other side of the boat went much better and is now
covered in a hard shell.

back to work.

[crazy ivan]

Possably a moisture problem when

Possably a moisture problem when you glassed the first side. Curing resin does not react well to moisture underneath it.