I filleted and taped the forward compartment of my Chesapeake triple and it didn’t go well. The fillets turned out a little smaller than anticipated but not too bad (probably a little under 3/4” in most spots). Glassing was the real problem. The weave didnt seem to want to wet out properly, or at least not as I expected it to. This lead to me putting on too much epoxy trying to remedy it. Even in the keel where the excess epoxy pooled up definitely beyond the thickness of the fiberglass, it’s still very visible. Also the edges didnt want to stay down and they are very rough. Getting it to lay flat without folding over was quite a challenge in spots, particularly rising up towards the bow. The viscosity of the epoxy was hard to work with a chip brush. I’m using west epoxy and the fast hardener because it’s Alaska in the winter so keeping my garage at 70f isn’t really an option. It was a pretty consistent 55f, and the epoxy was probably around 65f before mixing. I don’t particularly care that it looks terrible since it’s just the front hatch, but I’m not really sure where I went wrong and if it’s ok structurally. Thanks for your help!
It’s hard to tell from the pictures, but if there are air pockets I would try to figure out a way to cut those out or fill in with epoxy. Otherwise, I’d just sand it and give it another coat of epoxy to even it out. I doubt it will cause any structural issues.
I had the same kinds of problems wetting out tape, too, but here are a couple of ways to deal with it that has really helped me. First, add the tape to a filet that’s still wet. It really helps to get it set in place and the moisture from the filet starts wicking into the tape helping wet it out. Second, use a roller to wet out the tape. I use a 3/8 inch nap mohair roller. Don’t keep attacking the same spot if it looks dry. I have found that the epoxy can take a little time to soak into the tape. If I wait for a minute or two it usually goes from looking dry to wetted out. Finally, try using shorter pieces of tape. You don’t have to lay out the tape from one end of a filet to the other. You can use multiple shorter pieces. This is especially helpful over long lengths or curves. I overlap the pieces by an inch or two.
You can also try wetting out the tape before applying it to the filet. That is where I ended up, but you really have to breakdown the tape into manageable sizes. It has given me the best results.
Hi Yummyipa,
its always a bit hard to advise about this even with pictures…but when i look at your pictures it makes me wonder if the glass tape is potentially ‘old’ or contaminated or of a source that was meant for use with polyester and not compatible with epoxy.
the whiteness does not look to me like traditional air bubbles or failure to wet out properly…but looks more like a compatibility or contamination issue.
if you did not acquire your glass from clc or from a purveyor with modern stock manufactured for use with epoxy, i would proceed with care. a test piece of wood and cloth, perhaps indoors under more ideal conditions, is where i would start to see if you can get that glass to properly wet out. IMHO, i would not proceed with further glass work until you verify you can get your glass to wet out properly with a test block. (note - i would do this not only with the tape but with the glass you expect to use to cover the boat in later steps).
if you can get it good with a test block, do a second test block outside in your workshop and reconfirm you can get it to wet out properly.
can you try that and let us know what you find. then can make a recomendation about what to do with where you are at.
h
Once you’re sure your glass tape is OK as suggested above, and verifying you’re using tape, not cut strips, thus avoid all the stray fibers that occur with raw glas edges, here are some things to try. Most of these suggestions below are preferred techniques even if you ARE NOT having a problem with wet-out:
- After cutting to length for the seam you’ll be working on, roll up the tape and submerge it in a cup of well mixed, room temperature epoxy. Fiddle around in the cup a bit with a tongue depresser to work out air bubbles and froth if needed to achieve full wet-out. Gently squeeze excess back into the cup as you remove the wetted-out roll of cloth. Or you can “accordian fold” the tape into the cup, wet it out, then run it between two fingers as you pull it out and roll it as you do this. Either way works. It is OK to get the cloth pretty “dry” at this stage (not dripping) as you already know all glass fibers are coated. You can always add more weave-filling epoxy with your chip brush after the tape is in place if needed, and again when doing fill coats. Getting the cloth unrolled onto the seam can be a bit messy where hard to reach, where the seam is long, etc., so do your do your best to use some plastic and or tape to mask adjacent areas against drips, maybe use a plastic plate so that you can set the roll on it while you unroll it and manipulate the end into place, and a partner always is helpfull. And clean up drips before they harden.
- Wherever the plans call for it and/or it makes sense, lay the tape onto fresh filets that are still plastic. It does pay to let them firm up just a little, as then you lower the risk of deforming the filet when laying in the tape/brushing over the filet and pressing it in with a chip brush. Try to add the tape when the filet is firm, but not so firm that you can’t gently press hard enough to “imprint” the cloth weave into the filet.
- Whether the filet is already hard (and in that case has been sanded prior to putting on the tape) or still fresh, and whether using pre wet-out tape or not, I always lay down a thin coat of fresh epoxy along the seam where I’ll be laying in the tape. It helps with wet-out, and helps the tape “stick” in place as you get it into position.
- Consider using push pins in places like vertical surfaces where you’re having trouble getting the cloth to lay down or where it is trying to all off or fold over. Just be sure to go back and pull them before the epoxy fully hardens.
- In some areas (the inside curve of a bow, for instance) tape just wont want to conform to the acute inner angle at the same time it needs to take on a banana chaped curve. If the tape doesn’t like the geometry it is being asked to lay into, sometimes it might be necessary to cut a piece of tape from raw cloth, with fibers oriented on a bias. You can get good results with biased tape in almost any tough-geometry situation - just do your best to avoid pulling out too many strings while wetting out, and be aware you’ll have some sanding to do to feather in the edge prior to fill coats.
- Always try to use the fresh, wet, warm (60-80 F) when wetting out glass, whether talking about tape or large area jobs. Epoxy that is even BEGINNING to firm up a little does a much poorer job of wetting out. Don’t mix too large of batches, and when doing large areas, it is OK to pour out as much onto the cloth all at once as you’re sure that you’lll have time to roll or brush in. That gives the the epoxy time to sink into the cloth, and the working time of epoxy poured out onto the surface is much longer than that being exo-thermically heated in the cup. If it is very warm in the shop (85+), consider thinning the wet-out epoxy mix with about 10% alcohol. I often do this (Texas and Georgia) and have never had a problem - others might have different opinions on this technique.
- Finally, if you can, stick around to keep an eye on your glassing job as the epoxy begins to firm up. It is much better to go around pressing out any bubbles (open the surface with an ice pick to let out the air prior to pressing) and gaps while the epoxy is firm but sticky. You can corrrect many problem areas this way, much more easily than trying to open and fill bubbles or grind out folded over “flaps” or whatever after things have hardened up.
Good luck, you’ll get better with experience and expirimentation, and there’s almost no mistakes that can’t be fixed, anyway.
Thanks for all the good info. I did wonder about the tape itself. This is what I ordered and am pretty sure is what I got: 4 Ounce Fiberglass Cloth | 50 inch Wide Fabric | Fiberglass Warehouse - Fiberglass Warehouse . I’ll do some test pieces.
Now that it’s dry. Is there a good way to tell if something is a bubble or just thick, uneven epoxy?
Just wanted to add that, again due to pot-life considerations, don’t worry that cup-wet outs waste too much epoxy. If you can wet several tapes and get them quick-unrolled into position on the boat all as a first step, you’ll have a lot of time to go back and work with them individually to get them in finished condition. If you wet just one and spend a long time working with it prior to going to wet out the second or third piece of tape, you’ll find the epoxy left in the cup has hardened up - thus wasted.
Whoops, I meant this: 6 ounce Fiberglass Tape | 50 Yard Rolls | Fiberglass Warehouse - Fiberglass Warehouse . The other link is one of the large rolls I ordered.
And adding (not knowing where you are) my daughter lives in Fairbanks.
Well wetted cloth, with solid epoxy from surface all the way down to wood, will be virtually clear, independent of how thick the layers of cloth/epoxy. Maybe some of the cloth fiber “reflection” within laminate might be slightly visible. Any other appearance is indication of incomplete wet-out, or of a bubble.
I’m in Anchorage. It’s mostly been around 0F (which is a bit cold for us), not the -40F Fairbanks has been seeing! I just did a couple test pieces. Left side was layed down try, then dumped epoxy on it. Right side I wetted out the wood with a thin layer of epoxy for a ~5 min, then laid down the dry cloth. In both cases I had to spend several minutes tapping it with a brush to get it to the this stage, though I would say the pre-wetted one worked better. You can still see the weave on it moreso, but I think that’s just because it’s less epoxy overall. Maybe I was just ill informed about how much effort it would take to push the epoxy into the weave, and I was worried about disturbing the fillets. I’m betting the colder temps and thicker epoxy exacerbated it. Next go around I think I’ll do a smaller section, warm the epoxy up a bit more before mixing, and try a cup wet out.
Better alternatives to the cheap brushes for this? The hairs come out like crazy, and they work terribly for coating raw wood anyway.
I can’t take credit for figuring this out, but you can put a few dabs of CA glue on the brush where the bristles attach to the handle. Shedding bristles and unraveling cut cloth are two of the most infuriating aspects of fiberglass in my experience.
And as for the already completed bow, I’d love more help on best approaches towards 1) sanding down the rough edges and bumps. (Orbital sander can reach some areas but not all. Any thoughts on using 1 or more interface pads to get in corners? Interface Sander Backing Pad IP D150/MJ2-15 ) 2) Assessing what might be just a bump vs a bubble that needs addressing 3) anything else? Thanks all!
the left side looks pretty good and the technique generally comports to how you would apply epoxy - dry cloth on a dry surface, poor epoxy over it, but you need to work it in/wet it out with a spreader - not a brush.
when i do epoxy work and if you watch most ‘pro’ videos, the spreader is the tool for wetting out - not a brush. Plastic Epoxy Spreader – Chesapeake Light Craft
while i may use a brush, it will only be for hard to reach spots or to put a dallop of epoxy more into a space that otherwise it would be difficult to poor.
advanage of a spreader is you can quickly clean it up for re-use with denatured alcohold before the epoxy fully sets. avoids the ‘bristle’ problem.
but given what i am reading, you really should ensure you have preheated your epoxy. it makes a big difference.
i did look at the website you referenced for the cloth and tape…nothing manifestly obvious as a problem…it says its compatible with epoxy…so you will have to rely on your test patches to tell you if you have some kind of contamination on the material they sent you.
fwiw, the first time working with glass is always the most challenging and you are building a big boat in a cold place which makes id doubly challenging…so don’t hesitate to build some skills with some sacrificial sample bits to get the hang of it.
on a personal note, my first boat’s glass work was a hot mess and i almost burned the house down. but my skills developed and now its just muscle memory. enjoy 
I just want to second Jeff’s recommendation for pre-wetting the glass before applying it. That has the major advantage that unless the saturation is perfect, it never even goes near the boat. I started doing it that way some 17 years ago and have never had a bad wet-out since. I even use it when covering large surfaces, especially concave interiors. For large sheets of glass I wet them out flat on a table made from polyethylene-covered plywood on sawhorses. This method actually uses less epoxy then pouring it on and brushing/squeegeeing it.
BTW, loose threads can be controlled by taping the edges of the cloth with blue painters tape.
Laszlo
Hi Yummyipa,
just a note that notwithstanding we appear to be contradicting one another, laszlo’s point about prewetting is something that i also do particularly with tape application and smaller pieces. as you build you will develop a sense of how to smoothly transit between methods that best suit the situation
The key to doing a good job and why Howard and I are not actually disagreeing. Also wonderful justification for an enormous collection of tools
The stern went much better. Not perfect, but I’m pretty happy with it! I prewetted the glass, which helped a ton. Next time I’ll use a larger container, so it isn’t rolled up as much when wetting out as it was still a bit dry in the middle. Keel fillet was done with sawdust and colloidal silica which was hard to mix thoroughly. The West filleting blend worked better. I had some bubbles form later that I couldn’t push out but I was able to pop with a razor and the second coat filled well I think. Getting the edges of the tape to lay flat was still very tricky. They weren’t peeling up but the little loops didn’t want to stay flat. I’m guessing they’ll sand down easily though.
Given how long the cockpit is in the triple, I’m unsure about how to best handle it. Im thinking : fillet the keel then immediately lay prewetted glass, then repeat for each chine. After they completely cure , I’ll sand and be lay down the full sheet of glass working in sections with a small overlap. I’m totally sold on prewetting for the tape, but for the whole width of the cockpit, I think I would make a giant mess and probably end up with terrible wrinkles and snags. Is the best strategy to do a small batches of epoxy and thoroughly work in say a 6-12” wide section, then move aft, and do the same, repeating until the whole 12+ foot cockpit is done? I got an epoxy roller which I’ll practice with first.
For the larger areas inside my boat I laid the fiberglass it down dry and poured a batch of epoxy in the middle. I used a plastic spreader and a roller to work it in, spreading it from the middle outwards. It was relatively easy. The only issue I ran into was dealing with the frayed ends where I cut the fiberglass. The frayed ends like to get caught on rollers and other things.
Don’t wet out in a container. Cover a workbench or piece of plywood with plastic sheeting long enough for the piece of FG tape you are trying to wet out. Set the FG tape on top of the plastic, dribble on the epoxy, and wet out the tape with an auto body spreader.
If you want to save money you can buy System Three colloidal silica on Amazon for less than the West product. It is great stuff. If you have not read the West Systems article on fillets I would strongly encourage you to do so. They give some great hints about what you should look for when mixing filleting material (basically keep adding silica until the mixture is no longer shiny. Frankly, I don’t lay fiberglass on the fillet until the fillet has firmed up.
I found David’s method of pre-wetting on a bench to give the best results but it can require a long bench and not everyone has room for that (I don’t anymore, for example). The dry middles can also be avoided when wetting in a cup by putting the dry tape into a dry cup, pouring the epoxy into the middle of the tape roll and reaching into the cup with a gloved hand and squeezing and kneading the tape roll. Keep it up until the roll turns transparent and squeeze the excess back into the cup for the next roll. You can also dip your gloved finger into the cup and brush it over any dry spots.
I used this method to wet out 20-ft lengths of tape in a pint container when I didn’t have room for a 21-ft table.
Laszlo