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Hi, Mark is here. I run the website wooddiys.com Depending on the material used for its production, the glue can be animal or synthetic.

The animal glue

It is so-called because it is obtained from substances derived from animal organic compounds (skin, bones, nerves, muscles). It is sold in tablets (only for hot applications), in pearls or powder for cold applications. The hot glues are applied very hot, with a brush, and, at room temperature, cold glues, applying a clamping of the junction with clamps at least for 24 hours for hot glues and for 12 hours for cold glues. The sealing characteristics for the glues to be applied hot are excellent, discreet for those to be applied cold; joints do not withstand ambient temperatures above 7 degrees centigrade and suffer from moisture.

Casein glues

In fact, these are also part of animal glues, despite the addition of additives. They can be lactic casein or rennet casein; however, the latter has less adhesive properties. Normally the powders on the market already contain the necessary additives (powdered lime, soda ash, caustic soda, borax). It is mixed in water at room temperature in the proportion of l kg of powder, including additives, and 3-4 liters of water. Stir for 15-20 minutes until a dense, homogeneous mixture is obtained.

These glues are applied at room temperature with a brush; clamping must be done with clamps for at least 6-8 hours, provided the room temperature is maintained at 15-20 degrees centigrade. It should be borne in mind that the prepared mixture loses its adhesive properties after 6-8 hours after preparation, and the glue reacts with the tannin contained in the wood, producing stains on the surface.

Synthetic glues

The range of synthetic glues is very wide and in continuous technological development. In principle, they are divided into glues based on urea-formaldehyde, vinyl resins, phenolic resins, and cellulose. For each of the above families, there is a further subdivision. Normally glues based on urea-formaldehyde require additives (hardeners) of type and dosage according to the manufacturer's indications. They're all quick-release glues.

Many types of synthetic glue (for example, vinyl glues and cellulosic) do not require any preparation. Others are to be diluted hot or cold with additives, according to the manufacturer's instructions, and apply hot and/or cold (always according to instructions) with a brush, with a very thin and uniform layer; in any case clamping with clamps for at least 2-3 hours. Before applying the various types of glue, certain rules should be taken into account, so that the operation is effective and durable.

How to Apply glue on surfaces

Surface preparation

The surfaces to be glued must be flat, clean and smooth; and the presence of acids, resinous substances, powder, granules, heterogeneous affect the sealing of the seam surfaces must not be polished; a certain porosity improves the sealing; if you have to paste penises that have already undergone a similar operation, the glue from the previous must be carefully scraped to expose the bare wood.

The application of glue

The glue should be smeared with a brush evenly on both surfaces to be glued, avoiding to repeat twice on the same stroke. The layer should not be thick, but such that, after tightening, only small drops of glue come out of the outer edges of the junction. Tightening and drying. clamping must result in a pressure evenly distributed over the two contact surfaces. To achieve a good result it is necessary to comply with the indicated tightening times.

The maintenance of adhesive mixtures. Glues to be applied hot should never be allowed to cool (if they harden they should not be regenerated): whereas glues to be applied cold if not used immediately. they must not be left in contact with dry air. Do not mix glues with different characteristics. Remember that the addition of hardening additives ah “ shortens the storage time of the adhesive mixture. Do not store glues based on synthetic resins.

Surface finishing

The holes and cracks must first be putty. Grouting is done with a grouting spatula and with rapporteur putty. On the market, there is semi-pigmented mastic for non-transparent varnishes and transparent mastic for transparent buffer varnishes or for wood color varnishes. One or two hours after grouting} a first sanding must be carried out, which is carried out by hand or with electric disc polisher. As abrasives, you can use pumice powder, Emery powder, kaolin powder, diatomaceous earth, abrasive pastes.