AIB         Various man-made resins                                                            Thu 20 Sept 2007

Polyester resins and epoxy resins  I don't know the difference.  There may be other artificial resins too.  'Araldite' is a trade name and appears (according to Wikipedia) that it may be of several types of resin.

Polyester Resin
I have said on various occasions that the marvels we see today that outshine what was available, say, when I was a boy in the 1930s, is due largely to the chemists of this world.  Why can a motor engine run for two hundred thousand miles whereas in 1935 an engine was worn out after thirty thousand miles?  It's the oil and the quality of the steel; and both are vastly different to those used in 1935.  I am moderately well educated in the field of electrical theory, but chemistry is dark art to me.  They can now even tell you what colour a compound will be despite the fact that it has never actually been made, and only exists as a theoretical substance in the mind of some chemist in a laboratory.  Truly astounding!  Artificial resins are such an example of modern technology.

Many of these artificial resins are supplied as a liquid in a tin.  Pour out the quantity desired and add the appropriate amount of hardener, and just let the stuff cure.  In many cases the quantity of hardener affects how long the mixture takes to harden, but as always, too much will wreck the process.  Better too little than too much.

My outbuilding / workshop has a wooden doorstep.  One end of the step was rotten and I removed a lot of decayed wood before reaching solid timber at the bottom.  So I decided to do a repair.  I purchased a litre of polyester resin by email from CFS Partnership of Unit A, United Downs Industrial Park, St Day, Cornwall, TR16-5HY, Telephone 01209.821.028, Fax 01209.822.191.  I found the firm on the internet.  The tin has instructions on it, but I only used a little at a time so had to guestimate the quantity of hardener.  The fact that the bottle of hardener leaked after I unpacked it, meant that I erred on the 'too-little' side as I was short of the hardener. But although it may have been a bit slow to harden, its quality seems OK.  I'm not going to say what the price was because I think the salesman took pity on me when I told him I was disabled and couldn't get into town to buy a litre in Halfords.  But the packing was superb and the cost very modest.

Remember that the compound does not require air to harden it, so I poured a quantity of the mixture into the hole in the doorstep and covered it to keep out the rain should any fall before the stuff had gone off.  In my case because the hole was so large, I used little bits of wood to act as filler and let the resin wet the timber all round and fill in the gaps.  The hardened resin is almost transparent, so I will paint the finished repair with rosewood varnish stain to match the colouring of the old timber.

Evo-stick Wood Adhesive
This is sold in plastic bottles that are made to have the screw top trimmed to allow the white cream to be squeezed out of the bottle.  The stuff is specifically designed to glue wood together.  When cured the stuff is waterproof, although they tell you not to use it when the wood is permanently waterlogged.  Waterlogged wood starts to disintegrate anyway.

The advert that it is stronger than the wood itself seems to be true, at least with deal.  I have never used the stuff on hardwood.  If you glue two pieces of whitewood together, and when cured rip the two pieces apart using brute force, you pull some of the timber away from the weaker of the two surfaces.

When cured, presumably by evaporation (like emulsion paint), the resin is similar to cured polyester resin.  Whether there is an chemical in the wood that hastens curing, I do not know but airdrying seems to cure the stuff anyway.  But while uncured it can be washed away by plain water.

I fixed a wood screw into a shallow plastic cup so as to act as a stopper for the spout of the bottle.  The quarter-inch-deep cup was filled with goo and the screw immersed in the paste.  It took nearly a week to cure in the warm house, but when it had cured it was as if the steel screw was welded to the shallow plastic cup.

I intend to fill the small remaining gaps of the doorstep now that the polyester resin has cured.  The Evostick is a white cream, and being water-solvent is easily cleaned off of clothing.  It would be good for fixing domestic items together providing that you can hold them together long enough for the cream to cure.  Very clean and almost transparent when cured.