Smiths Fill-It Epoxy Filler – The flexible wood filler with epoxy strength

Rated 5.00 out of 5 based on 3 customer ratings
(3 customer reviews)

£34.00£275.00

Fill-It Flexible Wood Filler is the perfect partner to Smiths CPES for restoring wood. It is the Epoxy Wood Filler that lasts offering a permanent and watertight solution. It will flex with wood and is so waterproof it can be used below the waterline.

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Description

Fill-It Flexible Wood Filler is the perfect partner to Smiths CPES for restoring wood. It is the Epoxy Wood Filler that lasts offering a permanent and watertight solution. Do it once, do it Right.

Smiths Fill-It Epoxy Flexible Wood Filler Summary

  • Long working time
  • No sag
  • Easy to work
  • Easy to sand or carve
  • Flexible – to the extent that wood is
  • Cures down to -2 degrees (28°F)
  • High strength, can be drilled or tapped for fasteners
  • Waterproof – Can be used below the waterline for boat hull repairs
  • No Shrinkage

fill-it permanent waterproof epoxy flexible wood filler smiths 950ml

Technology

Fill-It epoxy filler represents a breakthrough in the technology of filling compounds. using advanced hydrogen bonding technology, it creates a high strength, light weight, non-sagging, easily sanded epoxy filler. It consists of an epoxy resin and a curing agent which are derived from natural wood resins, and so are very compatible with wood. We describe it as a flexible wood filler, as it is made of wood resins and flexes with wood once set.

Use and Properties

The two components of Fill-It epoxy flexible wood filler are slightly different colours in order to aid in mixing. The mixed colour is off-white, but may be coloured if required.The two components are designed to mix one to one by volume. When mixed they become a gel which may be smoothed and worked to a feather edge. After one to two hours in moderate weather it begins to harden, and cures overnight. As soon as it does not gum up the paper it may be sanded, and primers or paints applied. It is easily carved or drilled, and screws may be driven into pilot holes without cracking. It has sufficient compressive strength that it maybe be used to fill defects in ferro-cement boat hulls, and sufficient flexibility that it is suitable for wooden beams, windows and sills, doors or other parts of wood buildings as well as wood or fibreglass boat hull repair.

In order to ensure good adhesion of Fill-It epoxy filler to a surface, the first application should be a thin film smeared forcefully against the surface. An additional quantity may then be applied to build up to the required thickness. The uncured material may be tooled smooth and level by placing a clean new piece of clear 4-mil or 6-mil (4 – 6 thousands of an inch, 100 – 150 microns, or 0.1 – 0.15 of a mm, or the thickness of a piece of 80 – 120 g/sq m paper)  polyethylene sheet (In the UK this relates to a decent quality carrier bag – a ‘bag for life’ if you will) over the uncured material and using a squeegee or other tool to smooth the filler through the plastic. Leave the plastic film in place until the filler has cured, when the plastic film may easily be peeled off. In order to ensure adhesion of whatever primer or paint is to be applied next, it is recommended that Fill-It epoxy flexible wood filler be sanded, and then lightly over coated with Smiths CPES, before painting.

Use over Smiths CPES

Fill-It will bond very strongly indeed to surfaces that have been treated with Smiths CPES (Clear Penetrating Epoxy Sealer) but you must ensure that the solvents have evaporated fully prior to application. Your nose is normally adequate to determine this.

How Much Fill-It do I Need to fill my Rotten Wood?

Fill-It does not shrink, so a 355ml tub of Fill It will fill 355 cubic centimetres of void with no wastage. There are approximately 15 cubic centimetres in one cubic inch.

In the real world wastage does of course happen, so I would normally reckon filling voids of around 300 cubic centimetres or 20 cubic inches from a small Smiths Fill-It. If you have more ‘hole’ than that, you need the larger Smiths Fill-It, which contains 950ml of product, and will fill around 900 cubic centimetres or 60 cubic inches of void.

The easiest way to calculate how much void you have is to look at the hole, and imagine it as a regular three dimensional rectangle (a parallelepiped is what this is called, which is why no-one knows the name!), where the length, width and height are averages of the dimensions of the irregular hole.

Fill-It filler how much to fill hole

Thus, your rotten window frame with a 1″ by 1/2″ by 4″ rotten section requires 4 * 1 * 0.5 = 2 cubic inches of filler, = 30 cubic centimetres (30ml) of Fill-It flexible wood filler to restore it.

PackageMilliLitres (cc)Cubic Inches
12 US Fl Oz35522
2 US Pint95058
1 US gallon3785231

Mixing Smiths Fill-It Epoxy Filler

We have some specific notes on the thorough mixing of 2 part products on this mixing page, but reproduce the Fill-It specific details here:

Smiths Fill-It is a 2 part high quality epoxy resin filler. As such you MUST use two different tools to remove the part A and part B components.

Mixing ratios are 1:1 by volume, or 92 parts A to 100 parts B by weight.

Mixing should be done to within 10% accuracy, which can be done by eye normally although the use of scales is recommended wherever possible.

Unmixed Fill-It lasts pretty much forever, however, if stored in cold conditions (UK winters qualify here), you may notice that the blue part B component has formed crystals. This is not the product going off, but is reversible crystallisation within the very pure contents of part B. Heating reverses the process; we recommend loosening the lid slightly and warming the can by placing it in a saucepan of hot water and leaving it overnight. The crystals will have disappeared by the morning, making the product far easier to mix. A cool (50 centigrade) oven can also be used to good effect.

Fill-It may be coloured using Iron Oxide pigments of paint quality during mixing. We sell a Colouring Kit that can achieve the tones of natural woods, and full instructions for colouring Fill-It can be found here.

Mix the two-components on a flat surface (a piece of scrap plywood or plastic is ideal) using a paint scraper, stiff-bladed putty knife or other similar tool.  Use a smear-scrape-fold motion, scraping clean both the mixing surface and the tools occasionally.

Keep mixing until the colour is entirely uniform. For mixing to use under the waterline in boats, please read the more detailed Fill-It mixing instructions here.

The filler, if uniform in colour, is now ready to use.

Working and Cure times

curing times for fill-it flexible waterproof epoxy wood filler

Cleaning Tools

Unset filler can be removed from tools with many solvents, including our Epoxy Clean Up Solvent, or elbow grease and an old rag.

Set filler cannot be removed from many surfaces, so please clean tools thoroughly before the Fill-It sets hard.

Painting Over Fill-It Flexible Wood Filler

We really recommend a coat of CPES over cured Fill-It after sanding to promote paint or varnish adhesion. Fill-It and CPES can be purchased together t a discount as a Wood Rot Repair Kit from here.

 

More Information

Creators Notes – From the pen of Steve Smith

How to Mix two part chemicals properly

How to colour Fill-It Filler to match wood

Additional information

WeightN/A
DimensionsN/A
Size

355ml – 12 US Ounces, 0.95 Litre – 2 US Pint, 3.8 Litre – 1 US gallon

MSDS

Smiths Fill-It MSDS

Fill-It Part A SDS

Fill-It Part B SDS

3 reviews for Smiths Fill-It Epoxy Filler – The flexible wood filler with epoxy strength

  1. Rated 5 out of 5

    Does exactly what it says on the pack. this filler is much better that the usual 2 part fillers for wood. Both parts are a softer consistency which makes it easier to get them out of the tub and easier to mix. Excellent to sand when cured. Once painted the repair is invisible.

  2. Rated 5 out of 5

    Smiths Epoxy Filler. This stuff works! Used on superstructure of my wooden boat. Easy to mix, easy consistancy. And pretty easy to sand to a super smooth finish. Invisible once painted. Seems to be tough as nails. All good. I did not try mixing it with any pigment, though I will be doing so for another project. Again, expensive. But suspect long term will pay off. And Steve is a great vendor, very helpful phone conversations both before and after purchase. Thanks!

  3. Rated 5 out of 5

    (verified owner)

    This is by far and away the best wood filler I’ve ever used, and I’ve tried many products over the last 30+ years. It’s easy to mix, gives you plenty of working time, and sands to a perfect finish. I’ve recently used Fill-It to repair splits and minor damage in a 200 year old door frame, and I’m very pleased with the results – an invisible repair that should last forever.

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