For epoxy applicators we all use more or less the same tools – but where do the various tools – the squeegee, the brush (we give it a haircut) and the roller excel. How working time of epoxy is not just a matter of fast medium or slow hardener
Read below to find out more.
The Aim of Epoxy Coating your Boat
Epoxy keeps the water away from the wood, extending the life of your boat.
Expense of epoxy means that it needs to be applied in the most controlled method possible. Choosing the right epoxy applicator to apply the right amount of epoxy essential.
Not enough and the epoxy layer might crack when the wood flexes or just be absobed leaving the surface dry. Defects in a smooth shiny epoxy surface allows moisture in, apply too much and you’ll have an expensive and heavy vessel.
FAQ to solve boatbuilding problems – lots of tips and tricks for using plywood, epoxy and more
Why does my epoxy go off too fast? Use the Correct tool and correct method
Epoxy going off too fast is usually because of a poor approach to application. Only rarely is it a problem with choice of hardener.
I recommend standard hardener but work on technique to get the epoxy out on the surface.
I’ve spent most of my life living in hot areas (Adelaide Australia on the edge of the desert and the Philippines. I think in terms of the production environment and usually order the fast hardener because even if there is a cold snap the work will be ready to continue processing the next day.
Method has much more power than the speed of the hardener.
- Get all your work laid out for easy epoxy application. All parts should have been dry assembled to check fits – this is what pro builders do.
- Do any masking to keep the job tidy in advance during the dry assembly.
- If doing larger areas for the first time start off with smaller mixes of epoxy and do a central area. There is no need to mix all the epoxy at once. MIX CAREFULLY.
- Don’t let the epoxy sit in the mixing container – it gets hot and gels very quickly. It needs to go out on the surface or into the piping bag and piped out onto the gluing or filleting surfaces.
- Don’t be fussy at the beginning of the coat, use the fast tools like rollers and squeegees for coating or glassing … then swap to brush for the detail work.
- If gluing or filleting – after the piping bag use a glue stick to spread out the epoxy but don’t use the end of the stick which is slow – use the side like a butter knife and light pressure – it spreads out the glue super fast.
- Clean up any gluing ooze with a glue stick sharpened like a chisel – pushed along it removes almost all the residue/excess epoxy.
If you use the methods above the work will go quickly because of the preparation and setup and there will be half an hour or more to get the epoxy applied and the parts reassembled. Leave the epoxy in the tin and use a brush to transfer and it is too slow – you might only have 5 or 10 mins working time.
How many coats of epoxy should I use for best protection of my Boat
Three thin (but never ever thinned with thinner) coats of epoxy will provide the ideal level of protection for both laminating fiberglass, as well as encapsulating plywood and lumber.
The first coat will be partially absorbed by the wood fibers or soak in to the fiberglass, it is not supposed to have a sheen.The second coat will start to have a sheen as well as start to fill in the weave of 200 gsm fiberglass cloth.
The third coat will be the final coat and is sanded smooth for finishing ready for paint or varnish to protect from UV breakdown. Where the epoxy will never get much sun it can be left glossy natural..
Wet on Wet (or Wet on Tacky) is the most time efficient way to coat the hull – saves heaps of sanding.
Applying epoxy wet-on-wet is the best way, because you will only have to sand once when the three coats cure.
If each epoxy layer fully cures it is probably that the epoxy will have to be sanded between coats.
Wet-on-wet will give each coat a chemical bond, as opposed to just a physical bond if coats are over cured and sanded layers. However, with this method you will have to dedicate your entire day to just doing this, most of the time will be spent waiting for the previous layer to partially cure, but still tacky when you apply the next layer.
So it is best to organize your work and your life so encapsulate several items with all three coats in one go. This will also minimize the number of brushes you’ll have to throw away.
OK … now to the tools. What is each tool best at and why do we trim our brushes
The most common epoxy applicators are squeegees, brushes or rollers. In general, rollers give much more accurate and consistent metering of epoxy coat. Let’s run through the spreader options
Squeegee for fast application of mixed epoxy over an area
The squeegee – gives a very very fast spread and distribution. Also fairly good control of distribution … but there will be thicker areas of resin left by the edges of the squeegee as it moves. Not good at small areas when not much resin. Tapping the squeegee gently sometimes that helps get resin into a small area.
Squeegee products a good surface with few bubbles. Lousy at doing edges and corners. Can be effective on verticals with care.
If you don’t have a squeegee like above you can make your own epoxy applicator – cut out a piece of plywood with a really straight edge. Sand the edges so they are smooth and radius the corners slightly so they don’t catch the threads and pull the cloth about.
Foam Roller for doing areas and an even distribution of epoxy
Roller – slow/moderate distribution but best control. Can be hard to find good rollers for epoxy – quality resin distributors are a good place to start. Gem brand like below can be OK. There are specialist rollers with thin foam and a glue that doesn’t degrade in contact with epoxy normally available for major epoxy distributors.
Make sure you have a cut down brush handy. Cheap rollers are a source of heartache and a cut down brush is the only alternative – get a 3″/75mm one …
There are two ways of using a roller.
- Like a conventional roller
- Hold it from rotating and slide it slowly across the surface to smooth it off (photo above)
Can use a bit like a squeegee when coating wood by using a lot of pressure so the epoxy gets pushed. This doesn’t work on glass as the rough surface will destroy the roller.
Leaves small bubbles which are flattened out by holding roller so it doesn’t rotate and slowly and gently slide it over surfaces that still ahve roller bubbles.
Not a good epoxy applicator for corners or details. So need a brush too.
Give your Brush a Haircut before applying epoxy Resin
Best epoxy applicator for detail and complex or small areas.
Brush must be trimmed to 1″/25mm long for epoxy work (photo above). Long brushes can’t control the amount of resin.
Brushes are generally still not so good at controlling resin film thickness – brush marks means uneven distribution. So it makes sense to use a squeegee or roller first.
Sloooooow because strokes are short and width is relatively small, holds the least amount of resin.. Best for corners. Best at wetting out dry glass (takes considerable pressure).
Perfect tool for fast glass taping and getting glass over or into corners.
Gentle pressing in resin rich areas will suck up some excess resin that can be used for other areas.
Can use as a squeegee to a limited extent. Best for tensioning glass cloth out to the edge of the work and pulling out wrinkles.
Without trimming down the bristles … it can’t do any of this. It is a pressure tool … not like a painting brush – short bristles mean that pressure can be applied. Also effective to pop bubbles.
Useful Links to Epoxy Application Methods
Epoxy fiberglass Method 1 – Small Areas
How to epoxy fiberglass chines or joins between plywood boat panels
Epoxy fiberglass Method 2 – Complex Curves
How to do small complex areas on boats and canoes with epoxy/glass – double bias tapes and why does my fiberglass bubble on the corners and edges?
Epoxy fiberglass Method 3 – Large Areas – reducing the emotional pressure of the epoxy going off
Epoxy going off too fast when there are large hull areas to be glassed or coated – it is not hardener speed – it is boatbuilding work practice.
Saving Labour by epoxy precoating plywood sheets
And how precoating plywood sheets or boat and canoe panels saves epoxy and makes sanding easy –
How do I apply epoxy glue fast, accurate and clean
Saving Material and Labour with epoxy by accurately and quickly placing epoxy where it is needed.
Storer Boat Plans Catalogue
Our Boat Plans are listed here – Click Here.
