Repairs with silicone rubber and cotton composite
Introduction
Silicone rubber and cotton composite can be used for repairs of perished natural rubber such as old rowlock padding (Rubber oar stops with lugs) that is perishing after many years of service.
RTV silicone rubber can be used effectively to make and repair all sorts of things and I have described many such applications in a growing post that relates mainly to silicone rubber for backpacking gear. This current little project is about boating repair so it deserves its own post. I have used the word repair. However, I probably should have described the project as extending the serviceable life of an old natural rubber object. “But who would have searched for that!”
The silicone rubber/cotton composite repair
Natural rubber is a wonderful product that has had thousands of applications over many years. However, its Achilles’ Heel is that it slowly reacts with oxygen and perishes over time. This perishing is accelerated by having the item stretched from its original molded shape. Rubber oar stops must be stretched over the oars to ensure that they hold in the correct place. So the perishing is server.
Luckily, synthetic inorganic silicone rubber is immune to such perishing and makes a wonderful repair material when reinforced with a suitable fibre such as common shirt cotton. “They are very complimentary; the cotton strengthens the rubber and the rubber waterproofs, strengthens and preserves the cotton. Together, they are very easy to glue and apply to the rubber surface to be repaired.”
I started by impregnating shirt cotton with RTV Silicone rubber after diluting it 1:4 parts of mineral turpentine. Then I cut the cotton into long strips that would wrap several times around the collar of the rowlock pad. Similar wider strips were cut so that they could wrap around the rowlock pad.
The areas for repair were smeared with ‘neat’ RTV silicone rubber and the cotton ribbon was quickly and tightly wrapped around with more rubber between each layer. More silicone rubber was applied to cover the cotton. Then the finished repairs were sprayed with some water to accelerate the cure of the RTV silicone rubber.
Conclusion
The repair was quick, cheap and simple, even if a bit ugly and it did not involve a gaggle of toxic and carcinogenic chemicals that alternative glues often employ. The silicone rubber repair held the pad tightly in place and the oars were totally serviceable for another season of fishing and probably for many more.
This project also shows that RTV silicone rubber can be compatible with natural rubber repairs and silicone rubber/cotton composite is very suited to repairs that employ tensile or compression wrapping or binding. “The remainder of the rubber rowlock pads may get the same treatment when the splitting developed further.”
While investigating the proper name for these rubber pads, I discovered that the replacements were actually amazingly cheap. However, I think the method used in this post should be valuable for repairing natural rubber items that are expensive or simply out of production.
Tim
