posted 12-08-2011 03:51 PM ET (US)         

I always mix up batches in small quantities. I experiment with the amount of catalyst so that I have about 15-20 minutes working time, and try to use the batch I mixed up in 10 minutes. That way you don't waste material and ruin your tools. Have a jar of lacquer thinner ready to drop your brush in and also some lacquer thinner in a tray, to put your other tools in too, while you are mixing up a new batch. Oh, another thing have a batch of latex gloves, you will have to keep changing them if you get resin on your hands which is inevitable.

Figure out what you need for material and cut your mat, cloth, and or whatever you are using beforehand. Then set it out so you can just pick up the piece you need and glass it in and keep moving. Also some of the cheap resins will need to be sanded if they are kicked off before you add more glass, and some you can just keep on adding to, like if you don't finish in one day.

posted 12-08-2011 05:08 PM ET (US)         

Here is everything else you need to know. You can buy a half-pint and experiment!

posted 12-08-2011 10:05 PM ET (US)            

It is my understanding that wax is used for the final coat only to promote a full cure. It then can be sanded and cleaned with acetone after a full cure. The only reason wax is added to the top/final coat is to seal the surface from air allowing a full cure. When fully cured it sands better (doesn't gum up the paper), has better adhesion ability when correctly prepped and better water proofing properties... This can be done a number of ways; I use gelcoat mixed with duratec additive (no wax), some people use gel mixed with wax, and others use the same resin they put the glass down with but with wax added for a 'cure coat'. As long as the laminating resin is able to be sealed from the air using any of these methods it should fully cure.

So, I guess I am recommending you buy unwaxed resin and add your wax to the mix only for the final top coat.

posted 12-08-2011 10:51 PM ET (US)            

--what sort of wax

--where one buys the wax

--what proportions of wax to resin to use

posted 12-09-2011 10:09 AM ET (US)            

Resins are sometimes labeled "finishing" and "laminating". Finishing will have wax, laminating will not.
All the wax does is limit air exposure. Air exposure inhibits the curing process of laminating resins. If you apply multiple coats, the advice to add wax to the final coat is very good.
Wax paper taped over the small repair will also work.

Note: Air-inhibited, is laminating resin.
Non-air-inhibited is finishing resin.

Confused? Welcome to my club.

posted 12-09-2011 11:33 AM ET (US)            

If you are laying up multiple layers of fiberglass cloth or mat, use laminating resin. This will remain tacky on the surface after curing.

posted 12-09-2011 12:30 PM ET (US)            

Con

posted 12-09-2011 04:27 PM ET (US)         

If you buy Mini-Craft gelcoat for your Whaler, you can buy a premium grade that already has the wax in it.

So I guess JimH has never purchased any Whaler recommended gelcoat or he would already know this?

I believe the little paste containers alrealy have the wax in it also? I don't buy those.

posted 12-10-2011 12:28 AM ET (US)         

Standard color matches are also terrible, particularly with the old Outrage Gray color. Not even close. I mix the two as needed for any exact color match I need, any boat.

posted 12-11-2011 08:23 PM ET (US)            

You mention putting a layer over the areas you are repairing- if you use a very thin coat it will have a tendency to be a little stickier then usual. You want a little bit of volume for that.

posted 12-12-2011 10:34 PM ET (US)            

quote:

---

Polyester resin is the cheapest resin available in the marine industry and offers the poorest adhesion, has the highest water absorption, highest shrinkage, and high VOC's. Polyester resin is only compatible with fiberglass fibers and is best suited to building things that are not weight sensitive. It is also not tough and fractures easily. Polyesters tend to end up with micro-cracks and are tough to re-bond and suffer from osmotic blistering when untreated by an epoxy resin barrier to water. This is really cheap stuff.

---

That's from the link above to http://www.redrockstore.com/resin.htm

posted 12-13-2011 12:26 PM ET (US)            

I am not interested in making comparisons to epoxy resin. That is an interesting topic, but it is not at all my interest here. I mentioned already, I have some small repairs on my boat that I would like to finish with polyester resin, and I am seeking advice. I have not had good results in the past. So I have elicited advice about using polyester resin.

There are some previous discussions on this topic, but they tend to lack clear and concise details, including links to sources. For example, if someone recommends "adding wax," this is meaningless to me. I need to know what what what, what proportion, where to buy it, and how to handle it.

posted 12-13-2011 05:45 PM ET (US)            

-What specific product you have previously attempted application, and what result was achieved

-What specific instructions did you follow in your application

posted 12-13-2011 07:20 PM ET (US)         

Then folks chime in to give their advice no matter that they never had the pleasure of grinding glass in 90 degree summer heat, or watching on TV as some 'expert' does it.
I believe he is pulling our chain.

posted 12-13-2011 10:48 PM ET (US)            

The resins that are used in fiber reinforced composites can also be referred to as 'polymers'. Man-made polymers are generally called 'synthetic resins' or simply 'resins'. Polymers can be classified under two types, 'thermoplastic' and 'thermosetting', according to the effect of heat on their properties.

Thermoplastics, like metals, soften with heating and eventually melt, hardening again with cooling. This process of crossing the softening or melting point on the temperature scale can be repeated as often as desired without any appreciable effect on the material properties in either state. Typical thermoplastics include nylon, polypropylene and ABS, and these can be reinforced, although usually only with short, chopped fibers such as glass.

Thermosetting materials, or 'thermosets', are formed from a chemical reaction in situ, where the resin and hardener or resin and catalyst are mixed and then undergo a non-reversible chemical reaction to form a hard, infusible product. Thermosetting resins such as polyester and epoxy cure by mechanisms that do not produce any volatile by products. Once cured, thermosets will not become liquid again if heated, although above a certain temperature their mechanical properties will change significantly. Although there are many different types of resin in use in the composite industry, the majority of structural parts are made with three main types, namely polyester, vinyl ester and epoxy.

Polyester resins are the most widely used resin systems, particularly in the marine industry. By far the majority of boats built in composites make use of this resin system.

Polyester resins such as these are of the 'unsaturated' type. Unsaturated polyester resin is a thermoset, capable of being cured from a liquid or solid state when subject to the right conditions. It is usual to refer to unsaturated polyester resins as 'polyester resins', or simply as 'polyesters'. There is a whole range of polyesters made from different acids, glycols and monomers, all having varying properties.

There are two principle types of polyester resin used as standard laminating systems in the composites industry. Orthophthalic polyester resin is the standard economic resin used by many people. Isophthalic polyester resin is now becoming the preferred material in industries such as marine where its superior water resistance is desirable.

Here is a link to one manufacturer’s preferred Isophthalic (type 404 – tooling polyester resin) and their standard Orthophthalic (type 435 – marine grade resin) that are suitable for most repairs:

http://www.uscomposites.com/polyesters.html

Either of these would be used as manufactured for all but the final layer of the repair. If no chemical or physical means are used to eliminate air from the surface of the repair during the curing process, the lamination will cure to a tacky state. This is often desirable while laminating multiple layers and hence, I believe, lead to the common use of the term “laminating resin”. “Finishing resin” on the other hand, is commonly used to designate a polyester resin that will fully harden making it hard enough to facilitate sanding.

The addition of a surfacing wax to unwaxed polyester resin effectively changes it from a “laminating wax” to a “finishing wax”. Surfacing wax is not mold release wax as described elsewhere in the thread. This particular manufacturer sells only unwaxed polyester resins; therefore they sell surfacing wax to add to their resins as well as mold release wax (which is used to facilitate easy release from a mold). I suspect that other manufacturers may not sell a specific surfacing wax because they sell both “laminating” and pre-mixed “finishing” resins along with mold release wax. This may explain why confusion exists about incorrectly using mold release wax as a surfacing wax.

Here is a link to the same manufacturer’s surfacing wax:

http://www.uscomposites.com/solvents.html

Note that this manufacturer also sells distinct mold releases in spray on and wax forms:

http://www.uscomposites.com/moldrelease.html

posted 12-15-2011 08:27 PM ET (US)            

My company has been repairing fiberglass since 1964, thousands and thousands of repairs using poly resin, properly used it is what you would want on a boat manufactured in the same resin. Lets take a current "little" project on a 25', new stringers, full transom conversion, converting seating into cockpit space, new deck- we will be into this boat for probably 25 gallons of resin- imagine paying the extra for epoxy? Not alot of people will go for it.

posted 12-15-2011 08:39 PM ET (US)            

Great information. Question - Have you had any issues with shrinkage of a repair over a ten year time frame? Specifically, say a bolt hole pattern from a deck mounted downrigger or cleat showing up years after the initial filling and painting?

posted 12-15-2011 08:59 PM ET (US)            

I will go one further- if I told you that I have tried practically side by side comparisons of different resins and notice no difference would you believe me? Different fairing compounds, etc.
My view on it is that the cause of the shrinkage relies more on the BOAT rather then the resin. Give you another idea- we perform alot of repairs on boats that were manufactured with vacuum bagged epoxy resin. I have purchased the same resin directly from this company, I have vacuum bagged it, epoxy fairing, etc- and it is the worst boat you would ever want to repair in regards to shrinkage. Tried almost every epoxy resin on the market with no difference.

posted 12-16-2011 02:53 PM ET (US)            

I didn't know because there is other stuff being used by some boat builders, so I emailed Chuck Bennett at Boston Whaler and he replied that Whalers are built using polyester resin.

posted 12-16-2011 03:06 PM ET (US)            

I'm a noob about to start repairing my console. If I order the Spectrum in Desert tan, what tints should I order so I can fine tune the color. just black and white, or will I need more than that?

thanks