: Hi Everyone. First time posting here. I was refferd here by a friend from
: another website. I am working on a project that has me using Marine Grade
: Epoxy from Tap Plastic's. I have had mixed results with it and was wonder
: if there was a better epoxy system that you have had good results with? I
: am using the Marine Grade Epoxy to resin some Carbon Fiber, so it need's
: to dry clear. Here is a link to my project
: http://svtsupercharged.com/gallery/album10

: My problems have been.
: #1 Fish Eye's.
: #2 Spots in the clear resin.
: #3 Long dry times.
: #4 The resin has a weird greesey finish?
: Thanks For any help you can give me

Nice looking project, but it seems to be a rather involved way of making mirrors, or cases for holding LCD screens.

First, I'll try to give you some ideas on solutions to the problems you asked about. Then, if you stay with me, Ill offer some advice on how to do this whole project a bit faster and a lot easier.

fish eyes: there are lots of causes for this problem, but one of the more common ones is tiny traces of oil. People who have used brand new plastic mixing pots have discovered that there were traces of oils left on them in the manufacturing processes. So, wash all your tools with soapy water the day before if you can, and let them dry.

Spots are from crud. Someitmes you create that crud yourself by poor mixing. Portions of a poorly mixed batch might start to harden before the rest of the batch, creating lumps, which are invisible when applied, but which either folat to the surface, or stand above the surface as the liquid levels itself.

We commonly solve both situations by sanding down the epoxy surface until it is smooth. Then we restore the shine to the surface by coating with several thin coats of a varnish or polyurethane finish. The varnish and polyurethane are necessary on epoxy which is going to be used in sunlight. Epoxy does not tolerate a lot of UV light before it starts to get hazy, so to keep a clear finish it needs to be protected by something which will block UV light. Most varnishes and polyurethane coatings designed for use outside have UV blockers mixed in. You have a good variety of choices here, including the 2 part polyurethanes used for automotive finishes. Automotive body shops have a variety of products for rubbing out finishes so they give a dazzling shine.

Long dry times: Curing times depend on two main components: time and temperature. That is assuming the products are properly mixed. A mixture which has too much resin or too much hardener will not cure the same as one which is properly compounded. Accurate measuring is vital. Generally epoxy sets to a "green" stage, where it can be easily dented with a fingernail, in a matter of hours -- and then it slowly continues to cure over a period of a week or more, at room temperature. In colder weather it may not come to a complete cure for months.

People who have built kayaks in the winter have discovered this and simply accept it -- or they heat their shops, or buy special hardeners which are designed for lower temperatures. Similarly, there are special hardeners designed for warmer temperatures, too. Since these products are a major price item, you may find many postings in the archives of this board relating to whih material would be best for a given season or geographic location. You'll also find stories of woe turning to joy from those people who started with the wrong materials and later switched.

If you want your materials to harden faster, wait until after the epoxy has entered the "green" stage and it is no longer tacky, then gently heat it to about 200 degrees. For a project of the size youu are showing, you could probably jsut leave it the beam of a close lightbulb. Place a meat thermometer close by. You might want to set its probe on a piece of scrap black carbon fabric so it gets as hot as the project. A 100 watt bulb about 1 foot away will get things up to 150 to 200 degrees within a half hour. Move the bulb to keep the temperature around "poultry" (about 180 degrees) and let your project sit for a day or so to accelerate the curing.

Epoxies cure by polymerization. Molecules in the epoxy mix with molecules in the hardener, and when these components are stirred together they start to form crosslinked molecules. The crosslinking process an go on for a while, ans as more of these molecules merge together the material gets harder and stronger. Some of the plastics used create byproducts during the polymerization process. These are either trapped inside the matrix of the material, or they are forced out of the mass and end up as an ooze on the surface. The most common of these oozes is called "amine blush". This is easily removed with soapy water and a gentle scrubbing with a cloth or paper towels. Some people reduce the scrubbing by using a mild solvent like diluted vinegar, or water with a small amount of ammonia mixed in, and then a clear water rinse. You should ALWAYS wash off a cured, or mostly cured, epoxy surface before you apply a new coat of resin. If you are coating a piece which is at the "green" stage this is not so important.

If there is any blush remaining on the surface, some of it can float up through a fresh coat of resin to form fisheyes, or your spots.

The photo you show of an area that looks like it has cancer reminds me of a mess I had when when I mixed too large of a batch of resin, the pot got too hot to hold, and the material started to "kick" or gel in the pot. I tried applying it, and it just didn't want to flow at all.

OK, that's about all I can do for guessing at the causes of your problems.

Now, I am guessing that you want to make more than one or two of these things, or, that you may want to make something similar in the future. If so, then what you want to do is to make these parts in the same manner that motorcycle helmets are made. You want to mold them.

What you are doing now is "forming" them over a shape or form, or a "plug" as a male mold is sometimes called. In your case, since the "plug" remains inside, you can't easily make duplicates. by the way, it might be a lot faster to make you plugs out of styrene foam building insulation instead of particle board. You can work this with power tools if you must, or you can carve it with x-acto knives, or even shape it with a blunt stick. These will be lighter in weight, too. Hollow out areas and glue in small plugs of wood in those areas where you expect to later drive screws. Your fiberglass and carbon fiber covering will hold those wood plugs in place.

When you mold something you have to first create a "female" mold and finish it so it is mirror bright. Then you apply a waxy coating and a very thin layer of a "parting" material so your resin won't stick to the mold. Next you put in a layer of resin, which you allow to gel, then another layer of resin in which you embed your carbon fiber material. paint this with more resin and if you want a thicker and stronger part you build up more layers of glass cloth or carbon fiber cloth. Some people then put the mold and all the fillings into a large plastic bag and suk out the air with a vacuum pump. The vacuum in the bag allows air pressure to force the material deep into the mold, compressing the layers of cloth into a strong, compact composite. After the resin has hardened to a "green" state you can release the vaccuum and, since the part is still flexible, you can remove the part from the mold.

If you use a polyester or a vinylester resin instead of epoxy you can buy a prepared "gel coat" material which yo would apply as a first coat in your mold. this is thicker than epoxy so it gives a deeper "look" to the finished part. You would then saturate the cloth with your polyester or vinylester resin and lay it on the gelled gel coat, and prced from there. Polyester and vinylester resins are much more resistant to UV light, so you would not need to varnish them. These can be polished and buffed to a high shine with the same materials used for polishing fiberglass automobile body parts.

You may need to make two molds, one for the front and one for the back, and then join the pieces with a bead of epoxy cement. Or, if you think you may need to remove the LCD panel at some date, join the pieces with stainless steel screws. You could even use the screws which hold your hinges to the part to bind hinges and both pieces.

This eliminates the cutting of the particle board, the filling and glassing of the particle board forms, and all the intermediate steps. You end up with a part that not only LOOKS like it is made of carbon fiber, but is very light and strong because it really is MADE from carbon fiber.

Check out the website for www.Fibreglast.com they have some comments about the materials the sell, and they have some books and videotapes available which show how to make items from fiberglass reinforced plastics.

Hope this helps.

PGJ