Roller, Squeegee, Or Brush to increase Epoxy Worktime.
Brushes, Squeegees and Rollers all have advantages and disadvantages for boatbuilding epoxy coating. This explains and provides useful tips.
Brushes, Squeegees and Rollers all have advantages and disadvantages for boatbuilding epoxy coating. This explains and provides useful tips.
How common are Epoxy Resin allergies and what are there strategies for reducing the chance of building an allergy? I will discuss building strategies, materials choices and useful production work practices.
Sandpaper – don’t use COARSER THAN 100grit ON TIMBER TO BE GLUED (or Painted/Varnished). We provide reasons.
Judging their own work so harshly; one reason is that we all get used to looking at the boat construction from a few inches away so we over value both mistakes and an idea of perfectionism.
Most epoxy mixes are 2 to one resin and hardener. Or 4 or 5 or 6 to 1. Some companies offer 1:1 and push ease of mixing. But are they a good choice?
I’ve been in and around wooden race and recreational boats for a few decades now. As a designer who sells plans I can really only direct people towards the most tried and true methods that work just about anywhere. This article explains a large part of experience that leads to my approach.
Any paint or varnish can be turned into a non skid paint without buying anything more than some coarse grain sugar. The texture provides good footing and has no sharpness that will hurt your feet.
The basic problem is that end grain is highly absorbent so it can steal the resin from the join leaving insufficient for good bonding.
Just a simple wooden box with a lightbulb inside and a switch on the outside. The swing down lid has slots so the tops of the epoxy pumps are outside the box or a hinged lid you just flip up when you need to pump.
Epoxy that has not cured is a problem most of use come up against at least once. However it is unlikely to happen a second time as it’s operator error in 99.9% of cases. So what are the typical mistakes?
Battery Drills (most convenient) with a clutch and variable speed remove the need for dozens of clamps which can be a major cost.
Paint vs Varnish
Paint is more durable and will protect the epoxy and timber the best. But Varnish is faster and easier to apply. Methods and pointers
Varnish hides a rough surface better. If you have done a rough job the timber grain will hide it. Make sure the varnish contains ultra-violet filters. It is a photo from the Goat Island Skiff Calendar put together by the facebook goat group.
My usual plan is to varnish the inside of open boats and decide to paint or varnish the outside. Generally if you can store the boat indoors when not in use there is no reason to not leave the outside clear finished. But it is going to be left outside much of the time I would consider a painted exterior including the gunwales and remember to leave the boat upside down.
Types of Paint and Varnish
There are two basic types of paints and varnishes.
1. Two pot – which is very hard and durable, but can be hard to get a good finish with a brush and to touch up. You have to be careful of the fumes. No primer or undercoat is required.
2. Conventional varnishes – thin with turps, are easier to put on, but may remain soft for some time. The conventional varnishes often have a better gloss and I think they are much more pleasant to use (feel nice/smell nice).
Use varnish and paints according to manufacturer’s directions.
A professional finish is 90 percent dependent on getting the surface smooth between each coat – this is the BIG secret. There are no miracle methods or products.
My tendency, for maximum durability and best appearance, would be to use a two pot polyurethane for the outside, round to the underside of the gunwale, and a varnish on the interior. For rough use I would paint the whole thing.
Consider masking off some of the floor areas with masking tape including nice rounded corners and using a non-skid finish.
A caution with conventional Turpentine based paint over epoxy
Sometimes it is said that you don’t need a primer or undercoat when painting over epoxy.
This is possibly true of two pot paints – but still it is a good idea to use a high build primer so the colour of the wood doesn’t show through the paint.
But with conventional paints I’ve experienced a problem where the final finish paint never seems to harden if applied direct over the epoxy. It just stays wet or cheesy. The way to avoid this is to dewax the epoxy carefully (unless it is one of the newer low waxing epoxies which minimise amine bloom) then sand the finish and finally to apply the undercoat recommended by the finishing paint manufacturers.
For some reason undercoat never fails to dry properly – in my experience :-)!
New Products/Methods – Single pot polyurethane with Teflon.
I am not up to speed on it yet, but the people at Duck Flat Wooden Boats are getting excellent finishes from the new range of International/Interlux brand paints that have teflon added.
They use a small (3 inch – 75mm) soft foam roller, The foam on these rollers is quite thick but the diameter is fairly small – maybe 1.5inches (37mm): in Australia they are sold under the “GEM” brand. The rollers leave a level coat and the paint levels out significantly as it dries.
One trick to to run the rollers pretty dry. If there are lots of little bubbles being left behind no matter how hard you work the surface then you are using too much paint.
The result is a little short of a good average spray standard. Gloss is excellent.
Paint and Varnish Maintenance Guidelines
Hose the boat out after use.
If leaving it outdoors for extended periods turn upside down on a couple of bricks so that air can get under it and water can run off. If the epoxy coating is damaged put three coats epoxy (wet on wet) on the exposed wood and touch up with varnish or paint.
If varnish is continually exposed to sun it will need a light sand and two or three new coats every year (more frequent in the hotter states). Two pot varnish will go for a couple of years under the same conditions.
It is important not to let the timber underneath deteriorate – the whole coating will need to be sanded or scraped off and you have to start from the beginning.
With varnish the rule is that if you are trying to decide whether it needs a new coat or not, then it needs one NOW. This attitude will save you a great deal of maintenance.
Conventional paint can be given a fresh coat when it starts looking shabby (3 years?). Two pot paints should be good for 5 years or more.
Keeping the boat out of the sun will reduce need for maintenance many fold.
There are a number of labour and materials saving techniques that reduce labour and reduce the quantity and cost of epoxy used – wet on wet coating, one hit gluing
If ply sheets are precoated before assmbling the boat it saves lots of time. Here are some guidelines
This is a basic section on the stages of fibreglassing areas on a plywood boat, canoe or SUP. Many problems can be avoided by being methodical and setting up each stage carefully rather than rushing in.
Where a seam or boat chine is fibreglassed and the glass bubbles and will not sit flat or go around the corner – a simple trick for boatbuilding. This article shows how to make your own double bias tape.