Epoxy experience?

[rturbett]

Par,
Thank You. I consider myself proficient using the West System, using fast and slow hardeners, various fillers and additives, to achieve the desired results of a recreational boat builder. My two fears of trying a different epoxy are: handling characteristics and will it hold up long term.
Handling traits can be learned through practice and trials.
long term results can be learned from others experiences, but only as a guideline.
I am interested in finding the best way to deal with sags in vertical work. I am filling in 10oz glass cloth. I would love to not have to sand down the sags I have gotten with thickened west with slow hardener-probably put on too thick with a cooler temperature as well.
My thought is a thickened resin with a fast hardener, with the heat turned up after application.
Rob

[ahender]

From what I have read, Pro-Set is pretty much the best there is.

As for sagging, what about the other extreme, an extremely low viscosity epoxy that penetrates extremely fast, like Pro-Set?

Are you using epoxy to initially hold the cloth or a spray adhesive like 3M?

alan

[rturbett]

This is on the outer skin of a glass/balsa/glass hull built on a male mold.
I have no trouble wetting out the outer skin, in fact I wrap it in plastic to clamp it to the balsa.

It is the second and third layers of resin that have sagged on me in the past. I would like to eliminate having to longboard it between coats. The resin was mixed with 403 to thicken it. I did not wrap it after the initial coat- i suppose I could clamp a plastic film on it, but the less steps the better for me.
Rob

[ahender]

Maybe let each layer gel before you apply the next layer of cloth so that you get good adhesion and hopefully less sag?

alan

Originally Posted by rturbett

This is on the outer skin of a glass/balsa/glass hull built on a male mold.
I have no trouble wetting out the outer skin, in fact I wrap it in plastic to clamp it to the balsa.

Am I right that you mean the INNER skin? That is the one next to your core, on the outer side of the hull. !?
Does your time window allow to work "on the green"? That means the resin has geled, kicked, starts hardening, but you easily can remove it with any hard tool.
If possible you should layup EP in one go, every layer on the green predecessor.
If not, you must sand the surface anyway, blush or not! But the mechanical bond is never as good as a chemical one.
Sagging really is more related to skills than to the material, but even the pro´s have some sagging. Best way to remove, naturally, is immediately after kicking off with a scraper.
The thixothropie of the resin is (within some bandwidth) easily to control by additives. Usually making the overall properties of the matrix a bit weaker.
A thinner resin does not really help on the second or following layers. Just training and working on the tacky surface of the green layer helps.

Regards
Richard

[PAR]

403 is milled micro fibers. Alone it will sag to some degree, depending on it's volume in the mix. I very rarely use just one reinforcement in a thickened batch. If you add colloidal silica (406) to the mixture it will stiffen up considerable and not sag.

Yes wrap it if you can, which will control things. Another trick, but requires timing is to roll it out with a solid rubber or HDPE roller, with a piece of Mylar or plastic sheeting over the work. Get it as it's beginning to gel and you can get mirror results. Do it too soon and you'll have lap marks, too late and it doesn't do much and you're breaking molecular bonds.

[rturbett]

Apex,
This is for the outside of the hull. I am doing a 10 oz glass /1/4 balsa core?10 oz glass sandwich. It is being built over a male mold. I did a test hull tried a few techniques to get a smooth surface. When I tried to get it all done while green i ended up with a lot of sagging drips.

One technique that was effective at knocking down the high spots was running a utility knife razor blade across the surface held at a 90degree angle.
I would like to avoid having to do this.

Par, Thats funny about the fillers- I avoided using the colloidal silica because it was noted it makes things harder to sand. If I had used it, I may not have had to sand it at all!
I am going to do a few test panels- I think a combination of the different fillers, a faster setting epoxy, and the excellent idea of a mobile mylar sheet with a rolling pin (my poor man's HDPE roller) will work. My first hull is acceptable, but I would like less labor to get the desired result.
Oh, I am pretty sure I have an extra rolling pin lying around- I don't think my wife took back all the ones she's thrown at me!

Rob

[AndrewK]

Rob, 10oz cloth this is only approx 325gm2? peel ply would stop your resin drainout.