This is the fourth part of the tips and tricks selection to manage easily your epoxy works ; in this chapter we will focus on glass taping works
- glass fabric strengthening works : here we will talk about all that glass fabric works which aims to strengthen the structural joints, we will not talk here about areal lamination works like laminating the whole hull surface (this aspect will be the subject of the next chapter)
- work ALWAYS “wet on wet” : that is to say, wet the joint area with liquid resin, make the required thickened resin radius and then laminate the glass fabric over it, in a single process before the resin set ; this has several advantages :
- avoid sanding and using peelply on the radius before laminating
- have a perfect primary bonding on the joint that is to say a chemical bond among the resin of the radius and resin of the lamination
- my first choice as glass fabric for this kind of work: this is quite personal, my choice goes on a 300 g/square meters +/-45° biaxial fabric . it can be cut precisely without dismantling itself like wave roven fabric tends to do, it is a good compromise between stiffness and good capability of being drapable on the joint (different story for wide surfaces lamination, here my personal preference goes on 200-300 g/m2 wave roven glass fabric)
- shifting from heavy biax to lighter one: in several of my plans I recommend to use a 500 g/sqm biax to have a strong lamination in a single layer, this is fine as long as you can work the heavy biax properly ; as a matter of fact in the last years glass fibers fabrics quality is constantly getting worse, so you may have to work with very stiff biax 500 patches; in this case there is not any concern to laminate two layers of biax 300 instead of one layer of biax 500
- working sequence:
- as we said, wet the parts and make the radius
- cut the glass strips in advance
- tools required: scissors, a small roller, a brush and a bubble roller
- take on board a 80 cm x80 cm cardboard panel , wet it with liquid resin
- lean the glass strip on it, soak with liquid resin and roller (use the minimum amount of resin )
- place the glass patch on the joint, shape it by hand , complete the operation with the brush soaking the eventually dry areas, avoid to work too much on the radiuses
- go on, patch after patch on the whole reinforcement (avoid to work with too long patches, they tend to became difficult to handle if they are more than 60 cm long)
- overlapping patches of the same layers : it is a required pratice to have a structural continuity , few centimeters of overlap are enough
- the second layer: if a second layer is required by plans, you’d better do it “wet on wet” too.
- Take all the time the resin gives you to work on the patches, avoid wrinkles and spikes and make a clean job , don’t hurry , work meticulously and take care of lamination details, pay attention that all the fabric is soaked, avoid the “resin pools” on the side of laminations or on the lowest corners; you can use the bubble roller to compact the lamination to finish the job , paying attention not to push to much on the radiuses.
- curved areas laminations : if you have to laminate in tight curves and biaxial begins to make wrinkles, you can do small cuts to release the tension ; in these cases you may switch from biaxial to wave roven glass fabric which curves easier and is definitely a better choice to laminate complex shapes (but it is more messy to manage)
- work ALWAYS “wet on wet” : that is to say, wet the joint area with liquid resin, make the required thickened resin radius and then laminate the glass fabric over it, in a single process before the resin set ; this has several advantages :
- Peelply: what is it and when to use it. Peelply is a light polyester fabric that can be used a last lamination layer, soaked with a little bit of liquid resin (often the resin of the underneath layers is enough to soak it properly); the interesting thing is that once the resin set you can peel the peelply away simply pulling it, which is precisely its task; the resulting surface will be perfect for a next lamination session or to accept a layer of fairing compound without needing to be sanded or washed to remove the soapy layer (which is made by ammines, a chemical byproduct of epoxy setting process); my advice is to use it where and when you need a good bonding surface for a next lamination session, or where you need a clean surface for a following fairing session ; you can also leave it in place for days and pull it away when you decide to fair/laminate that area.
you can find the next chapter, dealing with big areas glass lamination here
few images to close this chapter, a typical filletting and glass tamping work on a Saltaspiaggia, a good example of “wet-works” scissors, full metal so that they be thrown in the acetone with no worries at all, a glass biaxial 300 patch and a wave roven glass patch so that you can see the difference .
