What to impregnate plywood for moisture resistance?

Why is it difficult to buy moisture-resistant brands of FSF, bakelite or laminated plywood? Usually, such material is more expensive, so it is sold only wholesale and by order. The question of what to impregnate plywood for moisture resistance can be answered by the following treatment methods:

• Treating plywood with oils - impregnation with water-repellent oily compositions (not paints!) that form a fatty film deep in the wood structure, followed by the application of varnishes;
• Use moisture-insulating primers for impregnating plywood - the antiseptic in the composition prevents the growth of pathogenic mold;
• Treating plywood with hydrophobic agents - applying hydrophobic compositions prevents moisture from penetrating between the layers of multi-layer plywood material;
• Reinforcing plywood with water-repellent fiberglass - it is necessary to fix the fibrous fiberglass on the plywood sheet with transparent varnishes.

You can use ready-made lacquer compositions 6T or 6C, lacquers for floor work, lacquers 4T and 4C (you can also use antiseptics like Pinotex, the main thing is that they are suitable for oils) to treat the surfaces of plywood. It is not recommended to cover plywood surfaces with polymer epoxy curing and polyester resins instead of oil, as they do not correspond in composition.

Oil for impregnating plywood

Remember that it is not possible to achieve moisture resistance of plywood simply by painting it. Layers of paint are prone to cracking over time, so it is not possible to achieve water resistance by this method!

Step-by-step instructions

We offer you an algorithm on how to make plywood waterproof at home using a simple tool - oil:

1. Apply heated oil to the prepared plywood sheet with a special brush. Dry the oil coating from moisture with a regular household iron or construction hairdryer (at a temperature of at least 150-200 °C). Then, alternate the layer of oil impregnation and drying as many times as the plywood surface can absorb.
2. Apply varnish to the surfaces treated with oil, paying special attention to the edges of the material.
3. To enhance the water resistance characteristics, apply reinforcing fiberglass, pre-moistened with turpentine (in "homemade" construction, cotton marl will also work). To check the degree of fabric adhesion, tap it with an end brush.
4. Apply a second layer of varnish (no earlier than a few days after the previous one). Make sure that the fiberglass material is completely dry.
5. Before applying the final layer of varnish (or suitable paint), sand the surfaces with fine-grained sandpaper, remove any dust and bubbles. You can speed up the sanding process by using a power sander.

To make the impregnation of plywood more reliable, it is necessary to additionally protect the plywood sheet's end edges, which are most vulnerable to moisture, with metal or plastic overlays.

If the steps of our step-by-step instructions were carried out carefully and in full, there is no reason to doubt such plywood. If the protective coating of plywood has started to "age" over time, covering it with a network of small microcracks, use coarse-grained sandpaper! It is already known what to treat plywood for moisture resistance, so remove the damaged top layer of plywood coating immediately, and then apply varnish (or suitable paint) to it.

Important! Plywood should not delaminate (even when trying to pry the edges of the sheet with a spatula or chisel). This will significantly improve the water-repellent characteristics of the future moisture-resistant plywood made by yourself! Do not buy plywood with defects such as scratches, cracks, or crushed edges!