Fiber glassing when it's cold

[grantstew8]

To be clear, I've no hands on experience with resins or fibreglass. I have researched and read up about it.

My workshop is a few degrees above freezing and I've mixed up some polyester resin with more than the required amount of catalyst. I've laid down some glass on the underside of the mudguards/fenders and it's taking ages to set.
The leftover resin in the plastic tub has solidified but the thin layer painted on are still sticky. I did it to check if it would work....it is under the wheel arch so no-one will see it unless changing a flat.

Is this pretty normal for it to take ages to set/cure/go-off?

I expect to get my wood burning stove up and running next weekend to keep the place a little warmer.

[Esteban]

I used epoxy to fiberglass, not polyester. One batch went bad because I mixed in more hardener than I should have. It was a very, very bad idea to add "extra" hardener. Instead of hardening better or faster in chilly weather it stayed gummy, never to cure hard. So I had to peel off the gummy firberglass with a heat gun and a metal scraper. It was a disgusting job on many levels. A big waste of time and expensive materials. I had a very sad day when I decided I had no other choice than to scrape it all off. It set me back weeks.

[grantstew8]

Gulp... I hope I do not need to do that ....

It pays not to rush at it, I suppose.

[nevadatear]

My experience is also epixy, but too much hardener does indeed NOT make it set better/faster. Normal to set up faster in cup/ thicker than thinner. You need heat.

[Esteban]

There are low temperature epoxy and hardener formulations.

I have made some boo boos while building my teardrop. So it has sat unfinished in my garage for a couple of years. I am about to restart building it. I will cut off the side walls mostly because the doors I made warped and I have decided to buy ready made doors which will not fit my existing, wider, door openings. I have also decided to build a Benroy instead of a more ambitious Grummnan II design. I'm learning to be more moderate in my envelope pushing.

I was a first time fiberglasser. Made some BIG mistakes. The big one was to get the ratio of hardener to epoxy wrong. As I wrote above MORE HARDENER IS NOT BETTER, it is horribly worse because it does not set up hard, instead it can stay gummy.

Still I like working with epoxy. I like that it allows you to more easily build a custom sized teardrop. It is cost competitive with aluminum. It's fun once you learn to do it right. Along those lines I will buy a scale to more accurately measure the resin and hardener. I like that it water/weather proofs very well. One thing I am worried about a little is that our winter weather here is weird, overly warm for the season. So I do not know what hardener to purchase.

My goal is to have a campable teardrop in time to go to IRG 5.0.

I did a lot of research. Posted ideas, and videos, in Skinning Secrets to help others who may be interested in using epoxy and or fiberglass.

[pohukai]

I've used both epoxy and polyester resin on different projects and prefer working epoxy. However, I used polyester resin on my camper and even in the 80+ F with the exact amount of hardener, it took a day to cure and several MONTHS for it to loose its tackiness. The smell is just horrible compared to epoxy. I've read, all resin will eventually harden, but during that time you'll have a difficult time keeping things from sticking to it; like bugs, dirt and the nice clothes when you accidentally brush up against it.

[grantstew8]

Oh no it's getting worse.... I'll need to get some epoxy after all.

Despite the bad news I've a recovery plan. If I'd painted my td with coloured polyester I'd be weeping big salty tears by now

Feel free to heap more on this post to help others not make the same mistake.

[michaelrsydney]

Polyester resin is easy enough to work with but does need some care. Epoxy on the other hand can be very poisonous and is obviously an expensive material to use for most jobs. You will probably find that resin suppliers will offer different resins in different seasons by adjusting the levels of promoters (not catalyst) in the product.

As has been stated it is not a good idea to try to accelerate the cure by adding catalyst at levels above normal. In fact too much will often mean delayed cure or no cure at all. The key to working in cold conditions is to raise the workshop temperature or if not possible gently heat the mould or job. Once the reaction has been kick started this way the natural exotherm of the cure will usually finish it off. High humidity levels will also be problematic to a proper cure. Is it ever a bit damp in Scotland?

Standard polyester laminating resin is designed to stay tacky on the surface so that subsequent layers will adhere without the need to sand first. If you do not plan to add additional layers, or to apply a coloured resin "flow coat", a little wax dissolved in styrene can be added to the resin mix before use. It is the moisture in the air which maintains the tacky surface and the wax forms a skin. If you do then want to add a surface coat you need to sand and wash the wax off. Polyester resins without a protective top coat are liable to ultra violet degradation.

[grantstew8]

Okay, so I now know I'm in over my head....

I can raise the temperature of the garage but the humidity is high 78% so epoxy may not be ideal anyway.

PLAN C
as plan a and b are not really suitable....

Garage floor paint
"Based on polyurethane alkyd resins which have been designed to withstand spillage and repeated cleaning. Ideal for use on most concrete and wooden floors in garages, warehouses, workshops and factories. Touch-dry in 3 hours"
http://www.screwfix.com/p/leyland-heavy-duty-floor-paint-tile-red-5ltr/33890#product_additional_details_container , (screwfix.com is rated "all ages")


I've used some of this paint on my garage floor and it's great. I would warm up the garage for a day or two before painting and keep it warm for a day or two afterward.
Now I think that would do the job of sealing and waterproofing it.

Fire away....I really need your honest opinions here.

I want to paint the td so it shines, so if this is not the right option, let me know what you think would be better: Consider I'm on a budget and just hosed £60/$90 down the drain buying the wrong stuff already.

[Esteban]

West System explains "Epoxy's cure stages" here: westsystem.com/epoxy-chemistry/
West System explains basic ideas about finish coatings here: westsystem.com/finish-coatings

The function of a finish coating like paint or varnish over an epoxy barrier coat, is to decorate the surface and protect the epoxy from sunlight. In doing so, the finish coating extends the life of the epoxy moisture barrier, which, in turn provides a stable base that extends the life of the finish coating. Together the two form a protective system far more durable than either coating by itself.
Protection from sunlight is a primary consideration in the selection of a finish coating. Long term UV (ultraviolet) protection of the barrier coat depends on how well the finish coating itself resists UV and keeps its pigments, or its shield of UV filters on the surface of the epoxy barrier coat. A high gloss finish reflects a higher proportion of the light hitting the surface than a dull surface. All other thing being equal, a white (especially a glossy white) coating will last the longest.

Most types of coatings are compatible with epoxy. Thoroughly cured epoxy is an almost completely inert hard plastic. This means most paint solvents will not soften, swell or react with it. However, it is still a good idea to build a test panel to assure coating compatibility.

it continues with descriptions of different types of finish coatings.

All of the West "How To..." are well worth reading and printing out for reference guides.

I gathered together many epoxy and fiberglassing resources here: Epoxy & fiberglassing resources

[grantstew8]

Cheers Steve

Any thoughts on the polyurethane alkyd resin floor paint?

[angib]

For either polyester or epoxy resin work in low temperatures, you can 'tent' the workpiece in plastic sheeting and use a portable electric heater to heat the workpiece up. With polyester resin, once the thermoset chemical reaction in the resin starts, it will heat itself up and fully cure. But leaving the tent and heater on overnight, or for several hours, is normal. Clearly you need to make it safe to leave on, and a electric fan heater with its own thermostat is the ideal heater - plus the fan circulates the air around to even the temperatures.
If anyone sees you doing this, you describe it as your "temporary post-curing oven" which, very loosely, is what it is.

[Tom Kurth]

To add a little to what Angib and others have said . . . (Disclaimer: I am no expert and am working from memory here, so don't bet the farm on what I say.) As I understand epoxy, heat causes epoxy to cure and harden. Usually that heat comes from the chemical reaction of the resin/hardener mixture. Spreading the epoxy in a thin layer reduces the amount of heat in a given area and therefore slows the curing. Confining the epoxy such as in mixing pot, concentrates the heat and speeds the curing (and can even start an unwanted fire). Applying heat from an outside source such as a forced air furnace, a radiant heater or an electric heat-gun can speed the cure. So, if your coat has not yet hardened, get the heat up in your shop and that should reduce the hardening/curing time. Good luck.

Best,
Tom

[tony.latham]

Grant:

I have not read each posting on this thread, so forgive me if I'm echoing another's thoughts. I have many years of working with both epoxy and polyester resins. (They go back long before doing cowling mods on my Avid Flyer BTW.)

Your polyester will cure just fine. It's going to take time and will be helped with an increase in temperature. There's a chemical reaction going off with it and you can't turn that back. Somebody mentioned "tenting" and that will work. The reason your pot of resin "went off" is that the chemical reaction is exothermic and heated itself up –it was compounded by the fact it was a large glob with minimal surface area to dissipate the heat. You'll see this happen no matter which resin you use. To avoid this, I'll put my resin in a disposable paint roller tray.

The advantage of polyester over epoxy, is expense and the fact that it is non-allergenic. I quit using the stuff years ago, but will go back to it if I develop a sensitivity to epoxy. But I like epoxy much better.

If you decide to change over to epoxy on the fiberglass you're working on, make sure you sand it down to the point where glass fibers are standing up. But you'd need to do that if you were going to add more layers with polyester, after it's cured.

Relax,

Tony

[Transit80]

Thankgod someone brought this up as Ive got this to do soon . Nice one Grant. .

Chris