Fiberglass Fin Building

I had always wet the surface first then apply dry cloth to the surface, less mess that way. then if its not enough resin then you can add some more with a brush...

Get rid of that stuff (polyester resin) for starters and pick up some US Composites or West Systems Epoxy. The Epoxy systems have almost no odor to them.

As Tim indicated, it sounds like you're using the wrong resins. A respirator is a better idea than ventilation, anyway.
I've done both, but for reinforcing fillets, I prefer to run the strip of cloth through the resin then use gloved fingers to squeegee all the excess off, and lay it down in place. Nitrile gloves are great for this, as they allow you to get "hands on".
If it's a joint down inside a body tube, a dowel can be used to position the strip. Lay the strip lengthwise down the end of the dowel, and allow it to fold in half. Then roll the strip off of the dowel and into the fillet. Takes some practice, but it's doable and works well.
-Kevin

Were you using polyester resin or epoxy?
What sort of fiberglass were you using?
-dave w

On both of these points, it sounds like you used polyester instead of epoxy. Polyester stinks, has a short shelf life, and is a PITA to work with. Usually just a few drops of catalyst to a large amount of resin. If that's what you got, trash it now.
Go with something like System 3, West, Raka, etc instead. In fact, buy or download the System 3 book for answers to most of your questions.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

I think you have two separate questions here; filleting and reinforcing.
ROL InfoCentral has some tips on glassing:
A Google search with "rocket fins fiberglass" should turn up a few informative links.
For reinforcing, I use thin epoxy (or alcohol thinned epoxy) on well sanded tubes with the fins mounted. I cut out a piece of cloth to go from fin tip, across the body tube, and to the tip of the adjacent fin with the weave crossing the fin roots in an "X" pattern. Allow some overlap on all fin edges. I wet the surfaces with a thin layer of epoxy, lay the cloth from one fin tip to the other, and fill-in dry spots or dab off wet spots. If you use thin (long setup time) epoxy, let it soak in a few minutes before applying the cloth. After the epoxy dries, I trim and sand the overlap. I use foam brushes for glassing. Work your way from one point to another in laying the cloth, don't lay the entire piece down at once. "Tugging" or pulling the cloth once it is down may pull it up and away from the fin/tube joints. You want intimate contact between the glass and rocket.
I don't have trouble with epoxy fillets cause I don't try to make them perfect. ;) I use twenty or sixty minute epoxy, dab it along the joint with a stick and let it "mold itself" into a fillet shape. I use FillnFinish after the epoxy dries to make up for my chad application.
I accidentally stepped on a LMR cluster bird with TTW glassed fins (don't ask). The only parts to survive were the fins.

This makes no sense to me.
Jerry

If you're trying to reinforce a plywood fin mounted on a Kraft paper body tube, forget the epoxy. Use Titebond and triangular balsa to reinforce your fins at the root. It's easier, lighter AND stronger.
Mark Simpson NAR 71503 Level II God Bless our peacekeepers

I'm not sure what I am using (and will look). It is some stuff I got at a auto parts store. My only previous experince was in helping a buddy glass a hood scoop to a car, and that was 25 years ago. Came in a 1 qt can and the ration is 1oz of resin to 12 drops of catalyst.
Thanks for all the info so far.
A

That's polyester resin. Epoxy, as noted, has much less odor (compared to the strong distinctive scent of polyester resin) and is generally easier to work with. Just be sure to measure accurately and mix very thoroughly for best results.
-dave w

David Weinshenker wrote in news: snipped-for-privacy@earthlink.net:
And different epoxies have different mix ratios,like 2:1 resin/hardener for RAKA and System 3,and West is,IIRC,5:1 or 2:1 depending on which hardener you use.
System Three has a really fabulous TRIAL KIT (for 10 BUCKS PPD!!)that gives you a generous sample of epoxy and hardener,PLUS different fillers like wood flour,silica,microballoons,and plastic fiber,and the VERY informative Epoxy Book,which every epoxy user should read.
You can't go wrong in buying this trial kit.
Disclaimer;I'm not an employee of S3,nor financially or otherwise connected to S3.

This should be in the FAQ.

They're also insanely expensive, and hard to find locally. I'd much rather use polyester resin that I can buy at any hardware store for $20 a gallon, than spend several times that much plus shipping (and waiting for it to arrive.)

Many epoxies are easy to find, if you look. I've found two local dealers for West, one of which carries the full product line.
-Kevin

Epoxy resin is about twice as strong as polyester resin. It also costs about twice as much.
Polyester is not so bad if you are vacuum bagging. Heck I might even recommend vacuum bagging even if its not really doing anything but keeping the smell down.
I get mine at the boat store down the street, but I live on the coast.
RDH8

I work for a fiberglass gelcoat company and went and had a long talk with one of the lab technicians. I was told that the absolute best solution for what we are doing is to use "vinylester resin". The tech claims it has the topmost strength yet not having the characterics of being brittle like polyester resin would have. I've so far glassed two rockets with it and have had one hard landing on concrete with nothing more than a little paint chip. Excellent stuff !! I use a 1 part DDM9 catalyst to 100 part vinylester resin for best results. Sorry but i haven't done any research on the web as to the location of this vinylester resin seeing how what I get is available at work but unfortunately not to outside sources. Any direct fiberglass distributor would have the knowledge as to getting the stuff i'm sure.

I've use TAP 314 "marine grade" resin from the local Tap Plastics - I think it's pretty similar to West or System 3.
(These days I tend to prefer Aeropoxy laminating resin from Shadow Aero unless I'm in a hurry - it's lower in viscosity and wets out _really_ nicely, but it is a bit more expensive and fairly slow-curing at room temp.)
-dave w

Hmmm... TAP has that (as well as several flavors of polyester and epoxy) - I might have to get some just to try. (Always good to explore options).
I wonder if it shares polyester's short shelf life - I've had the experience of getting a can of PE resin, using some of it, and coming back a couple of months later to find the remainder gelled or hardened in the can.
-dave w

David Weinshenker wrote in news: snipped-for-privacy@earthlink.net:
Healthwise,I wonder how it is for hobbyists?