And of course a fantastic demonstration from Dave!

Nah smallest first for me

Thanks for watching the video and for your response Nigel. It was a great team effort working with Tom and also Steve who filmed and edited. It is a point of huge and fascinating discussion ( Q. GRP repairs large/small patch first ) and answered by lab testing and pure logic. Firstly conducting a repair to an appropriately prepared polyester GRP boat with epoxy yields maximum adhesion compared with the use of the (polyester) resin it might have been originally built with, that’s where our lab testing is useful. Polyester resin has good, but not astounding secondary bonding characteristics yet yields excellent results when used in a reactive bond such as the lamination of a boat hull. Chopped Strand Mat doesn’t function too well with epoxy as it is unable to break the emulsion binder of readily available CSM ( it does work marginally better with powder bound CSM ). If a GRP repair was conducted with polyester and CSM then the random nature and the short 50mm length fibres of the CSM would make little difference as to the order of the patches. With structurally stronger and higher adhesion epoxy we tend to advise the use of superior strength Bi Axial fabrics ( +/- 45° stitched glass ). So applying the largest patch first yields the maximum continuous contact surface and uninterrupted fibre length when applied to the repair bevel ( we suggest 12:1 minimum ). It is also wise to measure the thickness of the hull and create a cutting pattern for the patches. Each 100g of fibre weight equating to app .1mm ( or 1/10th of a mm ) of finished thickness. Undoubtedly there will be some overfill of the repair that will require machining, With the largest patch applied first each patch will only have end fibres protruding around the perimeter of the repair. Consequently, the act of machining/grinding will maintain far more straight and continuous bi axial fibres throughout the epoxy/glass repair. It is quite feasible to effect a repair with the taper both inside and outside if the laminate is substantial. A long answer to a relatively short question I know, but hope you understand the logical and scientific explanation. Thanks again. Best regards. David.

bathing in it is a real bad idea, as your body builds up toxicity to it. I have old friends that cannot go near the stuff now as they get bad rashes & get sick if they do. (I was a polyester resin boat builder & did not have the same issues).

@@calthorp Haha .. I hear you. Of course I was being a bit facetious. I certainly try *not* to bathe in it and be as careful as possible, always wear protective gloves and clothing etc. But it seems that no matter how careful you try to handle the stuff, sometimes a mess or two can happen when you're using it frequently. Thanks for the reminder though. :)

@@sauter1 Yes nasty stuff for your body to absorb. I only use Epoxy when I have to, As most things can be done with polyester, its cheaper & far easy to use.

The ones that Sank their Boat🤔

Glad you enjoyed the video. Good question! It was West System 855 Cleaning Solution. More about it here: wessexresins.co.uk/west-system/cleaning-products/855-cleaning-solution/

Mithril

@@fernandofert9960 Fart

@@Barbreck1On your mouth.

Thanks for watching the video and for your response Mike. It was a great team effort working with Tom and also Steve who filmed and edited. It is perfectly feasible to conduct an Epoxy laminate repair and then follow up with colour-matched polyester gelcoat; there are a number of factors that affect a successful job however. It’s essential that this is conducted only above the waterline. It’s essential that the epoxy is well cured for a period of 5-7 days ( much less with professional heat lamps ). It is essential that the surface of the epoxy repair is, clean, dry, free from any surface contamination and scrupulously abraded with 80 grit minimum aluminium oxide paper. In summary (for GRP repairs) it’s essential that the polyester gel coat bonds to an unreactive, fully cured and well prepared surface…….after all gelcoat will cure if you spill any and will bond tenaciously to the floor or your shoes! We have conducted a wealth of adhesion testing to qualify this process. GBI in the US have their own occasional publication www.epoxyworks.com/index.php/applying-polyester-gelcoat-over-epoxy/ Very pleased to hear that you are using the correct materials and methods for a hull that may have been damaged due to osmotic blistering or delamination. For underwater repairs we always suggest an epoxy repair be finished with at least 4 coats of epoxy. There may be instances where the thickness of the hull or location of a repair requires grinding from both sides, again a perfectly feasible solution. There are numerous manuals that are very explanatory on our website. Thanks again Mike. Best regards David.

just let it dry, then ready for next product. saves plastic too