Save Money With the Less Resin River Table Hack! Using Only 1/3 Resin!!!

There is no denying that resin river tables have been one of the hottest topics in epoxy resin in recent years.

In our experience, many people would love to craft their own river table but, with costs of materials increasing all the time, at GlassCast HQ we wanted to share a great 'hack' for DIY'ers to create their own beautiful table using much less resin and therefore significantly reducing their costs!

If you are making a solid colour or metallic effect resin river table, then our incredible plywood core construction method is perfect for your project. This technique is aimed at DIY'ers and will help to save the maker a huge amount of resin, money and resources and still result in an identical outcome to a solid resin pour. 

Materials

• GlassCast® 50 clear epoxy casting resin (including hardener)

• Your choice of epoxy compatible pigment - must be solid colour or metallic powder for this project

• Your choice of live-edge wood

• Plywood sheet (or similar) to be used as the core material

Ancillaries

• Materials to create the mould box - we used melamine but other materials like polypropylene are suitable, or a surface covered in resin release tape

• Mixing buckets and mixing sticks

• Resin barrier tape

• Abrasive papers

• Mould release wax and filleting wax

• Wooden battens and blocks and clamps or weights

• Disposable brushes

• Nitrile gloves, glasses/goggles and a respirator mask (in case of insufficient ventilation)

• Cutting and polishing compounds and polishing pads

Finishing & Polishing

• Tools including DA Sander with a range of abrasive papers and a Power Planer

• Cleaning Equipment

• Table legs of your choice and Danish oil

• Jigsaw

• Power polisher

IMPORTANT SAFETY INFORMATION:

GlassCast 50 Resin is a chemical product.

Before storage or use you must download and read the accompanying safety and technical datasheet, available on the GlassCast 50 product page.

A Summary of the most important information is as follows:

•Always wear nitrile gloves when handling the resin or hardener

•Never touch uncured or partially cured resin with your bare skin

•Wear suitable eye protection when handling the resin or hardener

Although GlassCast 50 Resin is solvent free and has almost no odour you should still work in a well ventilated area or wear a vapour respirator mask.

Ambient Temperature, Pot-Life and Cure Time

Epoxy resins are highly sensitive to ambient temperature and moisture.

To achieve the best results, we recommend working in a room temperature of 20°C.

GlassCast 50 can be used in temperatures from 15 to 25°C but higher temperatures will reduce the pot-life of the resin significantly; at 20°C the pot-life is between 30 and 45 minute and the curing time is 48 hours.

Epoxy resins are very susceptible to moisture and humidity so it's important to make sure the environment is dry and heated.

Airborne Dust and Contamination

Whilst the resin is still in the early stages of its cure, it is important to keep airborne dust and contamination to a minimum. Before you begin you should ensure that the area you’re working in is as free as possible from dust and dirt. Although you need good ventilation whilst working on the project, in order to minimise airborne dust and contamination, we recommend covering the piece if possible during the cure.

Epoxy Resin For Your Project

The resin used in this tutorial is GlassCast 50, this is specially developed for use alongside natural wood to create professional quality projects. To ensure the best possible appearance for projects like forged carbon fibre river tables this resin is highly UV resistant, designed to degas itself during cure and can be cast in thick section in a single pour.

We recommend limiting pour depth to 25mm when poured into or alongside wood, it can be layered to achieve a greater depth if your river channel is deeper. GlassCast® 50 is highly polishable and can easily be buffed to a glass-like finish with it’s tough formulation making it hard wearing and less prone to scratches.

Choosing the Wood

This all comes down to personal preference and the overall effect you want to achieve from your project.

In the project, we selected a beautiful hackberry plank with it's naturally pale appearance and fine grain detail which contrasts so beautifully with the black pigment.

There are a few musts to consider when choosing the wood for your project:

• Ensure the slab is well seasoned, with a low moisture count
• Make sure the slab is as flat as possible as this will minimise work later in the project

Preparing the Wood

• Cut the slab down the middle - your supplier may be able to do this for you. Then when you flip the planks - placing the live-edges to face each other - this will create the river channel
• Remove any loose material from the live-edges, like bark using a mallet and chisel
• Key the live-edges using a coarse abrasive paper (120/240 grit), this will result in a good surface for the resin to bond to
• Then clean the surfaces and area, to ensure no dirt or dust remains

Setting the Wood up in the Mould Box

It's now time to construct a mould box around the planks, to do this you will need to lay out the planks and decide how wide you would like your resin river to be. Remember the wider the river is the more resin you will need and the larger the core will be.

There are several ways to create mould boxes when working with resin, for example using polypropylene sheets on wooden backing or base board and upstands covered in resin release tape which you can find guidance for in some of our previous projects. For this project we show you how to create a mould box using melamine boards:

• Measure up and cut out the base and sides
• Fix the upstands to the base using screws
• Make the box watertight using filleting wax - pushed into the cracks and corners
• Finally, apply release wax to the surface (according to the product instructions), this will ensure a clean release

Up to this point, the project follows a traditional river table process ... at this point we'll show you how to incorporate our amazing resin and money saving method - creating and inserting a plywood core!

The core is intended to take the place of the bulk of the resin you would ordinarily require, the aim of this step is to create a core that will mean that you will only need a 5mm (1/4 inch) resin pour around the core.

The size - thickness, width and length of the core - will depend upon the size of your slabs and the overall size of the table. We used a 24mm depth board, and our plank depth was 34mm, allowing for the 5mm resin pour top and bottom.

To create the core:

1. Begin by tracing the profile of the live-edge slabs on to the plywood sheet, including large knot-holes and cracks - as these can be deceptive and take up lots of resin
2. Give consideration to the angle of the waney-edges - you may need to set your jigsaw on an angle
3. Cut out the core
4. Make adjustments to the core if required - e.g. the angles
5. Create mini cores for sizeable knotholes or crack

Don't forget to allow for the 5mm gap on the top and bottom of the core and around the sides so that it will be fully encapsulated.

When making sure that the core 'fits well', use lollipops to lift the core by 5mm.

You are now ready to set the planks up in the mould box - using some wooden blocks covered in resin release tape and some clamps, fix the planks securely inside the mould box to stop any resin creeping under the planks.

Calculating how much resin you will need.

The very nature of a ‘live-edge’ on pieces of wood makes it difficult to calculate exactly how much resin you will need a project. There are some practical methods that can be used to measure the exact volume of an irregular shaped cavity - such as pouring rice or sand into the gap and then measuring the volume.

In most cases you can get a close enough measurement by measuring the river channel width in several places, then taking the average. It's then possible to work out the volume of the gap.

Because this method involves creating a plywood core which will take up the majority of the river channel, with the aim being to allow for a 5mm depth of resin around the entire core, in effect encapsulating it. The river channel should be measured approximately in length, width and depth to find the cuboid volume, as follows:

Length(in metres) x Width(in metres) x Depth(in millimetres)

The resulting number will be the volume of this shape in litres:

For example: 1.5m(length) x 0.2m(width) x 34mm(depth) = 11litres

The plywood used in the tutorial had a depth of 24mm which will be cut into the correct shape, this means that it would take up the following space:

1.49m(length) x 0.19m(width) x 24mm(depth) = 6.8litres

The total volume of the plywood core can then be subtracted from the total volume of the river giving a total for the resin required for the project.

The total is 4.2 litres meaning that a 5kg kit will be more than enough for this project.

REMEMBER - the total amount needed will vary depending upon your project size.

To ensure the resin you work with throughout the project is a consistent colour, we advise pigmenting all the resin (Part A) before mixing it with any hardener.

Pour the resin into a container that has a lid and add the pigment of your choice. We used a solid black epoxy pigment and added 5% - make sure you follow the manufacturers instructions. Mix the pigment thoroughly into the resin, making sure you scrape the sides and bottom of the pot and wipe some pigment across the pot to see if the colour is solid enough.

Mixing

It's now time to mix up the resin for the first pour. The depth of this pour needs to be 5mm and will form the base layer and the sealing coat of the live-edges. To calculate how much you will need take the length, width and depth as follows:

1.5m (length) x 0.2m (width) x 5mm (depth) = 1.5 litres

Using GlassCast 50 which has a 2:1 mix ratio means that we need to mix up 1 litre of resin and 500ml of hardener of GlassCast 50.

Using calibrated cups measure out the pigmented resin and the hardener and mix slowly and steadily for 3 minutes, periodically scraping the bottom and sides of the pot. Then transfer the mixture into a clean container and mix for a further 3 minutes - we call this double-potting and it helps ensure that no unmixed resin gets on to the project.

Pour the mixture into the base of the mould box (and knotholes if you have them) then using a brush paint the live-edges to seal them and leave to partially cure for around 12 hours at 20°C.

The first pour should have cured to the B-stage, to check this you can use a gloved finger and press the resin surface. It should feel firm but tacky but no residue should stick to the glove.

The clamps and blocks can now be removed and the core can be inserted and sealed. Mix up a small batch of the pre-pigmented resin - the quantity will depend upon the size of your project. Follow the double potting mix method again and pour the majority of the mix into the river and the knot holes if you have created individual cores for these.

Next, carefully place the plywood core into the river channel, lowering one side into the resin, then the other side before gently pressing the core down along it's full length to push out any air bubbles.

Once the core is in position, use a brush to seal and coat the sides and top surface, then leave to cure for a further 12 hours.

Check the resin has once again cured to the B-stage before mixing up the final batch - once again following the double potting method.

Slowly pour the resin into the channel and any knotholes/cracks - this pour should bring the resin level with the top of the wood.

Leave the resin to fully cure - for GlassCast 50 this is 48 hours - but check your product datasheets.

Check the resin has fully cured, then remove the slab from the mould box - if you prepared the box well it should release easily.

To machine the surface, we set up a router on a sled and completed several passes over each side of the slab the trimmed the edges on a table saw.

After routing we noticed a few small imperfections - tiny chips in the resin surface which we think was possibly caused by moving the router too fast - if you have any imperfections simply follow these instructions:

• STEP 1: Before filling any small holes or imperfections, thoroughly clean the surface using a vacuum cleaner and if necessary, wash and thoroughly dry the surface before moving on to the next step
• STEP 2: Mix up a very small batch of resin and hardener and add the pigment to match the main pour as closely as possible. Then using a lollipop stick, carefully drizzle the mixture into the holes and allow to fully cure (for a further 48 hours) before moving on to the flatting and polishing stage

Once the repairs have fully cured, the flatting and polishing can begin:

Flatting

Using a Dual Action Orbital Sander (DA) will make light work of a job like this one.

We advise working through the grits from 240 grit, up to 1200 grit.

It's important that you don't move on to the next grit until all marks are removed from the previous one or skip grits and when you get up to the finer grits on the resin we recommend wet sanding.

We are asked about sanding and polishing so often that we compiled a special tutorial to help people get great results which you can view in another of our Instructables here!

Before moving on to the polishing stage, we recommend protecting the wood from the polishing compounds you will be using. This helps to avoid staining the wood whilst polishing the resin. There are lots of products readily available from DIY stores - it really depends upon the appearance of the wood you're aiming for - we used Danish Oil which we simply applied in a few coats on a lint-free cloth, allowing it to fully dry before moving on to the final stage - polishing. 

Polishing

Using a power polisher and foam pads we applied a polishing compound to the resin river to bring it to a full-gloss and finally to give it an extra shine we applied our Topfinish gloss compound to give it the wow factor!

After Care

Here are a few things to remember when looking after your epoxy resin project:

• Hot Objects - You should not place hot objects directly on to the resin (pots, pans, plates or mugs) as this may mark the surface. Instead use coasters or heat proof mats. If you do find that hot objects have marked the surface it can be flatted and polished again to remove any marks.

• UV Light - GlassCast® 50 has been designed to have the best UV stability of any epoxy resin on the market and should withstand years of indirect sunlight with very little effect. However, common with just about all materials of this nature, prolonged exposure to UV light, particularly direct sunlight, can eventually cause some change in the appearance of the resin. For this reason, finished GlassCast® projects are not recommended for outdoor use and should be kept away from direct sunlight where possible.

• Scratches and Marks - GlassCast® 50 is a very hard wearing plastic and will hold up to the rigours of light daily use without marking. However, accidental damage can be caused by sharp objects scraping over the surface of the resin or from things being dropped onto it. If this occurs, these can be polished out using the same process that was used for the initial sanding and polishing ; i.e. abrasive paper (for coarse scratches) followed by polishing compound to restore the gloss.

The final step was to attach the legs and it looks incredible!

The amount of resin used on a traditional river table build was cut to 1/3 which saved so much money and materials, without compromising on strength. This is a fantastic 'hack' which can be used in any solid colour or metallic effect!

So if you're interested in making your own resin river table at a fraction of the usual cost - this is the project for you!

We would love to hear what you think of this project, be sure to let us know your thoughts and if you have any questions don't hesitate to ask.

Thanks for reading our Instructable :-)