Epoxy is a great ingredient in boat building and repair, including fiber boat repair. Its use is not limited to boats and can be used in general woodwork, even in domestic repairs, provided that the slightly salty price is absorbed. If I remember correctly, it is technically called “thermoset plastic”. It consists of two syrup-like ingredients that come in separate containers: “resin” and “hardener”. You mix these two in varying proportions depending on the manufacturer of the epoxy system. When you mix it in the proper ratio, an exothermic reaction that gives heat to the outside begins and the epoxy gradually hardens. First, the gel (or jelly) stage goes through a given stage, that is, it comes to a jelly consistency, then this jelly gradually continues to harden and becomes stiff. Let’s say it “freezes” if you want, though freezing actually resembles cold, whereas epoxy freezes by heating, but whatever. Frozen epoxy is an extremely strong adhesive with excellent waterproofing properties. I’ve read from multiple sources that a well-made plywood-epoxy connection is stronger than plywood itself. You can work on epoxy until it reaches the jelly stage. How long this will take depends on several factors, and these are explained later.
Let’s call the mixed resin and hardener an un-thickened (or thin) epoxy if no other ingredients have been added to it. With thin epoxy, you can insulate your material (plywood and wood for us) against water. It can also be used as an adhesive, but this is the latter preferred as a bond of the same strength can also be obtained by making the epoxy slightly thickened. When it is thickened, both epoxy is used more economically, and it is difficult to keep the syrupy thin epoxy at the junction. Fillers called “filler” in English are used to thicken the epoxy. Almost every epoxy manufacturer also produces various fillers. Each filler depends on bond strength, color, ease of sanding, etc. has different characteristics in terms of. Generally, powdery fillings are much cheaper than epoxy itself. So while it is possible to substitute other things as filler, it is a more secure way for amateurs to purchase directly from the epoxy manufacturer. When you pour the resin and hardener into a container and mix well, you get the thin epoxy. In this mixture, you then add the filling until you get the desired consistency, stirring constantly. A terminology has been developed according to the consistency of the thickened epoxy.
Where and how is it used?
Insulation (Coating)
When you want to insulate your wood or plywood against water, you use thin epoxy. A brush can be used for this job, but you have to throw it away at the end because nothing can dissolve the cured epoxy. So use the cheapest brush you can find. If you are insulating large surfaces like hulls, there are better ways than using a brush. You can pour some epoxy on the surface and spread it with a sponge roller. In my experience, the best way is to pour the epoxy again and spread it by making circular movements with a smooth semi-rigid plastic (squegee in English). Even better if you do this so that the angle between the surface and the plastic is as narrow as possible. You will minimize the formation of unwanted air bubbles. Since the more epoxy penetrates the surface, the better your insulation will be, it is useful to sand the surface first. This process provides better penetration of the epoxy and also enables you to get rid of foreign substances (such as oil) that may be present on the surface. Of course you need to clean the sanding dust. More than one layer of insulation is generally recommended for boats.
Wetting
Although thin epoxy can be used directly as an adhesive, it was stated that thickened epoxy is preferred for this job. Just like insulation, the strength of the bond depends on how much the epoxy penetrates the surfaces to be bonded. If thickened epoxy is applied directly to the bonding point, the material will absorb some epoxy from this mixture and your bond will be weakened as the amount of epoxy remaining in the mixture will be reduced. Therefore, both surfaces must be wetted with thin epoxy before thickened epoxy is applied to the bonding point. It is worth noting this process, as plywood, especially the edges of plywood, absorbs a lot of epoxy. The most economical application is in the form of wetting the surfaces after preparing the thin epoxy in the container, then adding the filler to the thin epoxy remaining in the container and starting the bonding process by thickening it. If you do not, be careful to apply the thickened epoxy before the epoxy freezes on the wetted parts.
Fiber fiber application
You use thin epoxy when applying fibers. Spread the fiber, pour some epoxy over it and spread it with a roller or plastic. Make sure that there are no air bubbles between the fiber and the plywood. If you notice a bubble, walk to the side and get rid of it. It is enough to use only enough epoxy to make the fiber transparent, and if it is more, it is harmful. After reaching the jelly stage, but before it has fully frozen, apply the next coat using the same method. As the fiber tape is usually coated on the paste, the application here is a little different. First, spread the tape over the fresh paste and fit it well with a roller brush or your finger. We don’t want air bubbles, but don’t distort the still soft paste while doing this job. Then I suggest you wait 5-10 minutes. The tape will absorb some epoxy from the putty below, and its parts that absorb enough epoxy will become transparent. Apply thin epoxy to the non-transparent parts until they become transparent. You can use a normal or roller brush. Again, be careful not to press the paste too much and distort its shape. Finally, look again for any air bubbles and remove them if found.
Lamination
Lamination offers an elegant solution to many problems encountered in boat building. For example, the D4 may require thick plywood, such as the rudder blade or keel, and you may not have it. Or, for example, it may be necessary to bend and bend a thick wood. If it is impossible to give the desired shape to the part of that thickness, the shortest solution for amateurs is lamination, that is, the method of obtaining the desired thickness with many thin parts glued on top of each other. For lamination, first clean the parts, sand them, wipe off dust and wet both surfaces thoroughly with fine epoxy. Then cover one of the surfaces with thickened epoxy in ketchup or mayonnaise consistency and fasten them together. You can use torture, weight, whatever you find. There are a few things to consider. If the laminated parts are small or thin and long, you can use thicker epoxy (mayonnaise). On the other hand, if you are sticking pieces with large surfaces together, it is useful to prefer a thinner consistency (ketchup). This is because it reduces the possibility of air bubbles remaining in between. Since this is a serious problem for large surfaces, drill a lot of holes in the top surface (I drill one hole every 10cm x 10cm) to escape the trapped air. Then gently fasten the pieces together and rest assured if the epoxy mixture seeps up through the holes. One last but very important note: The strength of the joint is not proportional to the clamping pressure. Actually, the opposite is true. If you tighten the tortures and remove the remaining epoxy completely, you will get a weak bond. When gluing with epoxy, it is necessary to attach the parts just so that they do not move. As a result, do not apply too much pressure!
Sticking
Same as explained about lamination that needs to be done. You clean and sand the places to be glued and wet them with thin epoxy. Then you thicken the epoxy until it reaches the desired consistency. Mayonnaise or even ketchup consistency is fine if you don’t work against gravity. If you are working against gravity, it is useful to make the epoxy a little thicker and make it shockella so that it does not flow. Then you apply the epoxy to the adhesion area and attach the parts so that they do not move. Be careful not to over tighten.
Paste, fill gap and surface smoothing
When you tighten the parts that you have glued with thickened epoxy, a little of the epoxy will overflow. Let’s call the U-shaped curve putty (English fillet) that will come out if you spread this overflowing part with your finger or anything over the adhesion area instead of taking it. Our aim is to leave a paste layer just like on the glass edges. Putty makes the connection stronger by distributing the load over a wider area. You can use your finger to apply the paste properly (don’t forget to wear gloves). Spoon or flat wooden sticks that doctors use to press the tongue while looking at the throat are recommended for this job. Of course, you can also use things that you can cut from scrap pieces to the radius you want.
For best results, the thickness of the paste should be around the thickness of the bonded plywood at its thickest point (ie on the line that exits 45 degrees from the joint). The length of the paste sideways, ie the length from the junction to the edge of the putty area, should be greater than the thickness of the pasted plywood (1.5 times a good choice, so the total paste thickness is 3 times the plywood). If the epoxy that comes out when you tighten the connection is not enough to provide these dimensions, you need to add it.
I think there is no need to explain what filling the blank is. You start by wetting the thickened epoxy floor covering price areas. Then you apply the thickened epoxy to the area and shape whatever goes in your hand. Surface smoothing (English fairing) is technically actually filling the gap. However, the gaps are not deep here and the surfaces are very wide. It is actually the job of the bodybuilder to smooth the small dents in your car with paste instead of hammering them. Sure, the car has a hammering option, but you can’t hammer a wooden hull. We are talking about filling the slightly dents of a large surface to obtain a smooth surface as a result. Again, you start by wetting the surface with fine epoxy. Before applying the thickened epoxy, it is useful to wait for it to become jelly. It is easiest to apply the thickened epoxy with the plastic part mentioned earlier. When your epoxy is completely frozen, you sand it well. You do not need to use a filler with very strong bonding properties for surface leveling. So, choose the filler you use to thicken the epoxy from easily sanded ones. Generally, the bonding strength of easily sanded fillers is low, while those that are sanded harder have high bonding strength.
Things to watch out for
1. As far as I know, epoxy is not carcinogenic. However, it can cause allergies in prolonged contact. Therefore, when working with epoxy, wear gloves (rubber working gloves, cheap nylon gloves if you cannot find it) and avoid contact with the skin. Protect your eyes very well, it should not smudge. Do not breathe epoxy vapor and emery dust (use a dust mask). Detailed information on health issues is available on the boxes. Once the epoxy is frozen, it is no different from the plastic you know, and it is harmless.
2; in an epoxy form on your clothes, tools, etc. it finds its way into contamination, so it’s a difficult substance to work with. Clean your tools with paper towels before the contaminated epoxy freezes. Frozen epoxy cannot be cleaned with water. Although some chemicals are sold to dissolve unfrozen epoxy, I don’t know how effective they are, since I don’t use them. It seems to me best to clean with paper without freezing. Once frozen you are out of luck, but you can remove it by sanding or grinding.
3; We mentioned that epoxy is an exothermic reaction that gives heat when freezing. If you prepare large quantities, the epoxy in the container can get very hot. When it gets warmer, the freezing process accelerates, and when the freezing process accelerates, more heat is released. For preparation, people often use paper or plastic disposable containers, and when mixed in large quantities, sometimes these containers can even ignite from heat. Therefore, it is useful to work with small amounts. If you pour the epoxy into a large-bottomed container after mixing, the freezing process will slow down and less heat will be released, since the heat will be transferred to the environment easier.
4; If you attempt to apply a new coat on the previously applied epoxy, if the underlying epoxy is not fully frozen, it will chemically bond with the new layer and form the strongest bond. If the underlying epoxy is completely frozen, then it is not chemically bound to the new floor. In this case, we have to mechanically ensure the bonding between the layers, so you MUST thoroughly sand the underlying frozen layer before applying the new epoxy.
5; Especially in cool and humid environments, a thin layer in the form of a wax may form on the frozen epoxy. This substance is the result of a chemical reaction and is completely harmless. However, we need to get rid of it, as it can fill your sandpaper and cause problems. Fortunately, this is a water-soluble substance. Therefore, it is useful to wipe the frozen epoxy with a wet paper towel before sanding.
6; It does not adhere well or at all to epoxy plastics. So when working with epoxy, you can cover your table and wherever necessary with nylon. If you do not do this, the leaking epoxy rudder bar can stick to your table forever. If you don’t know if it will stick to a certain substance, do a test with tiny pieces.
7; The only bad feature of epoxy is that it is sensitive to ultraviolet (UV) rays. It is said that UV light breaks down the molecular bonds within the epoxy, weakening the epoxy over time. I don’t know how long this period is. In fact, the epoxy droplets I accidentally spilled are still stiff, even though they have been in the sun for a year. Nevertheless, it is useful to follow the recommended one. If your epoxid work will be under the sun, you should paint it. Do not use light-colored paint in hot climates like Turkey, particularly recommend because there is more likely to affect the temperature of the frozen epoxy. If you want it to remain transparent, you should use a UV-proof varnish. Standard yacht varnishes do not have this feature.
8; It can be used to bond materials such as metal, styrofoam and even stone other than epoxy wood. I even glued glass. It should not be forgotten that the better it penetrates the substance, the stronger it will bond. Therefore, if the surfaces to be bonded are smooth, you must sand them thoroughly. Some manufacturers sell special kits for metal applications (especially aluminum).
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