Secret for wetting out 1708

Have few years of experience fiberglassing but only recently tried using 1708 and have hard time wetting it out. I could probably completely wet out 10 layers of CSM plus 5 layers of 1700 in time it takes to wet out a single layer of 1708. Plus, I end up flooding it with really unreasonable amount of resin. Recently, I started placing it with CSM side up and wetting it out and then turning over - this makes wet out process marginally better but still a huge chore. Tried with both VE and PE and same results.

Am I missing something? It makes so much more sense just to get CSM and 1700 separately.

 

Some brands of glass wet out easier than others. If you are buying the cheap stuff it will be very inconsistent.

Wet out the surface generously, then lay down the fabric, now apply it generously to the fabric. Don't mess around with just dabbing at it with a brush. Pour it on heavy and use a fuzzy roller, in some situations a squeegee works well to move resin too.

There are other methods like wetting it out on another surface and then putting it in place, but they tend to be more of a hassle in most situations.

 

Turning it over sounds really painful, And highly likely to produce undesirable results Like stretching.
When I prewet, I roll the wetted material up on an appropriate piece of tubing, then carefully roll it back out on the surface, a little bit at a time, making sure it’s flat and in alignment as it unrolls.
Make alignment marks with a magic marker to orient the piece correctly.

 

Fabric weight is an average. However, different diameters and shape of fibers can greatly affect the wetting and other physical properties of the fabric. Some years ago I did a research project on separator material for AGM batteries, which is fiberglass mat. They were having quality issues on production. The good quality mat had diameters with less than 10% variation. The low quality mat had diameters with over 400% variation. Both had the same nominal weight.

 

Should not be a problem wetting out a 1708 (DBM with mat) with VE or Poly. Could be your resin viscosity. Highly viscous /high shear resin makes it hard to wet out fabrics. Try using metal rollers to massage the resin into the cloth. Corner rollers for compound surfaces. Short nap rollers are great for laying out evenly the resin but takes some cajoling to completely wet it out. Carry some nails or ice pick to burst out those persistent bubbles. In general, I use paintbrush trimmed to about 1 1/2" length. These stiffling brushes is great for tabbing stiffeners.

Check your datasheet for the sizing used in 1708 style weave. Some use chemicals compatible only with certain type of resin. Sizing is applied to allow greater wet out. Most sizing now is compatible with poly, VE, or epoxy. Some don't as they are used only for non boat applications such as commercial fiberglass sheets and roofing materials. You must have gotten a weave that has no sizing (or it got wet).

 

40% on substrate, balance on top; reserve back 10% for trouble

use a bubble buster fin roller

don’t work below 72F or you’ll go way over on resin%

 

You’re not missing anything. 1708 is naturally hard to wet out, and using separate CSM and 1700 is easier, faster, and uses less resin.

 

@mvoltin . . . I'm late to this party, but I have done a lot of 1708 over the past 5-10 years. I use a wet-out table and plastic sheeting on the biaxial side of the cloth, CSM side up.
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I trowel the resin around the cloth with a putty blade and let it soak into the cloth for about 5 minutes. The cloth should be fairly transparent by then.

I use 1 ounce of resin for every 40 sq. in of cloth . . . you can go as low as 1 oz./50 sq. in. , but I wouldn't go any less.

Then I pick up the piece and put it on the substrate. Bigger pieces can be hard to handle in this fashion, so I sometimes fold the piece in half, flip it over to let it saturate the other half.

 

I was a Epoxy guy for some projects and found the Epoxy to be thick and required much efforts to make it clear.

Thickened and airboat hull and used poly for the first time and it was thin and wet out quicker.
Note! Not a glass expert but plenty of projects and associated practice.

BWP

 

one square yard of 1708 is 9 square feet or 1296 sqin and at 1:1 ratio; you would use 25oz resin or 51 square inches per ounce. If you wetout 40 sqin you are wetting at 51/40% or 127.5% or 1.27:1 resin to glass.

pretty good numbers; I always try for 1:1 which is the 51, but colder temps or losses to the substrate all drive it up and I am almost always needing a bit more..so I size up the extra needed and run in the resin ratio and make the hardener 1 ounce, resin x ounces minimum batches and am always ready for it..