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#1
posted to rec.boats
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fiberglass repair question
A corner of my 18' cc o/b boat got knocked off. It's at a spot aft where
the gunnel, transom, and flat top side of the gunnel all come together. The spot is approx 4" diameter. I'm fixing to stick some auto bondo or similar on it and then mold/shape for the right contour. The question is how to be able to smooth it on with minimum surface roughness. There used to be a number of tricks for doing that, such as a paint stirrer paddle kept wet by dipping in water. Is this still the easiest way to be able to soft mold the patch and get it close to where it needs to be before I start shaping when dry? If I need to, I can finish it with glazing putty, before painting. |
#2
posted to rec.boats
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fiberglass repair question
RB wrote:
A corner of my 18' cc o/b boat got knocked off. It's at a spot aft where the gunnel, transom, and flat top side of the gunnel all come together. The spot is approx 4" diameter. I'm fixing to stick some auto bondo or similar on it and then mold/shape for the right contour. It can be difficult to get that stuff to stick, but it's way cheaper than epoxy fillers. The question is how to be able to smooth it on with minimum surface roughness. There used to be a number of tricks for doing that, such as a paint stirrer paddle kept wet by dipping in water. Is this still the easiest way to be able to soft mold the patch and get it close to where it needs to be before I start shaping when dry? No, use a modern molded PVC putty knife. Slipperier than a wet stirrer and has a good chisel point, also wider ones can be had. Another trick is to use wax paper, folded along the desired corner. Tends to trap bubbles, so get them all out... and don't wrinkle it. I have been using painter's drop-cloth plastic sheeting for molding fiberglass the past year, works great and leaves a perfect finish. If it wrinkles, you can pull it flat again, and it's easy to chase out all the bubbles. But it doesn't do corners well. Fair Skies Doug King |
#3
posted to rec.boats
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fiberglass repair question
RB wrote:
A corner of my 18' cc o/b boat got knocked off. It's at a spot aft where the gunnel, transom, and flat top side of the gunnel all come together. The spot is approx 4" diameter. I'm fixing to stick some auto bondo or similar on it and then mold/shape for the right contour. The question is how to be able to smooth it on with minimum surface roughness. There used to be a number of tricks for doing that, such as a paint stirrer paddle kept wet by dipping in water. Is this still the easiest way to be able to soft mold the patch and get it close to where it needs to be before I start shaping when dry? If I need to, I can finish it with glazing putty, before painting. Having read the other answers; it seems you're not going to re-glass the area just cosmetically fill the hole & then reshape & finish??? I guess you're happy there is no structural issue??? The deck to hull joint in way of the transom &/or outboard well is fairly highly stressed??? Anyway, (i) Use a polyester filler, it will adhere to freshly ground clean & dry polyester fibreglass OK. The filler has little real strength & if the area is structurally stressed & flexed it will crack etc. (ii) Experiment a little so you get the amount of catalyst just right, so it takes about 15 minutes before the filler starts to "gel" (you need to experiment a little because the amounts of micro balloon fillers in the resin can vary even from batch to batch & of course you need to adapt to your particular temps humidity etc) (iii) Do the filling in several stages, the first to well below the final level needed & each time let the filler just start to gel then shape it with a u profile surfoam blade (just hand hold it without the blade holder it's light & easy to manipulate, because the filler is the consistency of cheese or soap & will easily grate off in slices, if it doesn't you've let it cure too long & no amount of "sanding" will ever get a proper shape, so grind & re-fill) long smooth cross hatched strokes & look along the boat, corner etc to get it right. (iv) Once you have the filling & surfoam shaping up nearly to the final level, take a plastic filler applicator & cut small but deep "V"s along one edge (e.g.1/2" deep on a 1/4" base say 3/4" apart). Then apply a coat of filler & carefully scrape it off with the V'd applicator. This should leave you with nice parallel little ridges of filler. (the pros put a bit of tint in the ridges so they're a different colour to the other filler) (v) Once the ridges have gelled & cured a bit so they're strong enough not just to crumble, use a long board to sand in the "final" shape. Even though the ridges are relatively hard compared to the cheese of (iii) it shapes & sands very quickly & easily because you're only sanding skinny ridges. (vi) Once you're happy the shape is perfect then you can use a non V'd applicator to fill in between the ridges, then after it's cured (unlike the surfoam you can't sand filler if it's too soft, just clogs) start sanding with an orbital sander (no courser than 80 grit) & here's the trick, sand till you just start to uncover the tops of the final shaped ridges & no further (that's why the pros use tint, they can see it "through" the overlaying filler as they sand down). (vii) After you have that then start surface finishing with filler scraped into the 80 grips marks sanded off with say 120 then again scrape filler hard over the surface into the swirl marks & sand till all imperfections are gone. (viii) If you want to use gelcoat to refinish then put it directly onto the filler with that sanded surface, never ever try to put gel coat over a primer or "paint" (where does he get this stuff???:-)) (ix) The gel coat will not harden on the outer surface (gelcoat has no wax in it & you shouldn't ever add any either, but once you've put it on & it's just started to gel cover it with cling wrap or even paint on PVA water soluble release agent (this does the same as the wax & seals the gelcoat from the air so it can cure full depth. (x) Peel off the cling & sand with ever finer wet & dry, lots & lots of water & always with a little sanding block (i.e. do not sand it with hand held wet & dry, you will not get a good shine at the end) (xi) Machine with cutting compound & if the colour of the gelcoat is a good match you'll be proud of it. K |
#4
posted to rec.boats
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fiberglass repair question
Saw a trick recently that suggested using the edge of a new single edge
razor blade to smooth along the edges of a gelcoat repair. Has a nice clean edge and is just flexible enough to make a perfect transition between the original surface and the filler. Just use it at an angle like a putty knife. Butch "K. Smith" wrote in message ... RB wrote: A corner of my 18' cc o/b boat got knocked off. It's at a spot aft where the gunnel, transom, and flat top side of the gunnel all come together. The spot is approx 4" diameter. I'm fixing to stick some auto bondo or similar on it and then mold/shape for the right contour. The question is how to be able to smooth it on with minimum surface roughness. There used to be a number of tricks for doing that, such as a paint stirrer paddle kept wet by dipping in water. Is this still the easiest way to be able to soft mold the patch and get it close to where it needs to be before I start shaping when dry? If I need to, I can finish it with glazing putty, before painting. Having read the other answers; it seems you're not going to re-glass the area just cosmetically fill the hole & then reshape & finish??? I guess you're happy there is no structural issue??? The deck to hull joint in way of the transom &/or outboard well is fairly highly stressed??? Anyway, (i) Use a polyester filler, it will adhere to freshly ground clean & dry polyester fibreglass OK. The filler has little real strength & if the area is structurally stressed & flexed it will crack etc. (ii) Experiment a little so you get the amount of catalyst just right, so it takes about 15 minutes before the filler starts to "gel" (you need to experiment a little because the amounts of micro balloon fillers in the resin can vary even from batch to batch & of course you need to adapt to your particular temps humidity etc) (iii) Do the filling in several stages, the first to well below the final level needed & each time let the filler just start to gel then shape it with a u profile surfoam blade (just hand hold it without the blade holder it's light & easy to manipulate, because the filler is the consistency of cheese or soap & will easily grate off in slices, if it doesn't you've let it cure too long & no amount of "sanding" will ever get a proper shape, so grind & re-fill) long smooth cross hatched strokes & look along the boat, corner etc to get it right. (iv) Once you have the filling & surfoam shaping up nearly to the final level, take a plastic filler applicator & cut small but deep "V"s along one edge (e.g.1/2" deep on a 1/4" base say 3/4" apart). Then apply a coat of filler & carefully scrape it off with the V'd applicator. This should leave you with nice parallel little ridges of filler. (the pros put a bit of tint in the ridges so they're a different colour to the other filler) (v) Once the ridges have gelled & cured a bit so they're strong enough not just to crumble, use a long board to sand in the "final" shape. Even though the ridges are relatively hard compared to the cheese of (iii) it shapes & sands very quickly & easily because you're only sanding skinny ridges. (vi) Once you're happy the shape is perfect then you can use a non V'd applicator to fill in between the ridges, then after it's cured (unlike the surfoam you can't sand filler if it's too soft, just clogs) start sanding with an orbital sander (no courser than 80 grit) & here's the trick, sand till you just start to uncover the tops of the final shaped ridges & no further (that's why the pros use tint, they can see it "through" the overlaying filler as they sand down). (vii) After you have that then start surface finishing with filler scraped into the 80 grips marks sanded off with say 120 then again scrape filler hard over the surface into the swirl marks & sand till all imperfections are gone. (viii) If you want to use gelcoat to refinish then put it directly onto the filler with that sanded surface, never ever try to put gel coat over a primer or "paint" (where does he get this stuff???:-)) (ix) The gel coat will not harden on the outer surface (gelcoat has no wax in it & you shouldn't ever add any either, but once you've put it on & it's just started to gel cover it with cling wrap or even paint on PVA water soluble release agent (this does the same as the wax & seals the gelcoat from the air so it can cure full depth. (x) Peel off the cling & sand with ever finer wet & dry, lots & lots of water & always with a little sanding block (i.e. do not sand it with hand held wet & dry, you will not get a good shine at the end) (xi) Machine with cutting compound & if the colour of the gelcoat is a good match you'll be proud of it. K |
#5
posted to rec.boats
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fiberglass repair question
Butch Davis wrote:
Saw a trick recently that suggested using the edge of a new single edge razor blade to smooth along the edges of a gelcoat repair. Has a nice clean edge and is just flexible enough to make a perfect transition between the original surface and the filler. Just use it at an angle like a putty knife. Butch Thanks Butch I'll pass it on. Another it's not exactly "new" but have been seeing lots of people glassing upside down hull surfaces lately, always causes a worry:-) but they tack plastic sheet to a table then lay the glass on it & wet it out, lift the plastic & take to the hull, then they carefully tape the plastic to the bottom of the hull & roll the glass/resin out through the plastic sheet (i.e.with the plastic still there). Once the laminate is completed they slowly peel the plastic off, & yes it does pick up small areas of glass but once off a quick roll out gives a perfect job, upside down, not overly resin rich, no drips, no waste, no mess. Thanks again for your tip. K "K. Smith" wrote in message ... RB wrote: A corner of my 18' cc o/b boat got knocked off. It's at a spot aft where the gunnel, transom, and flat top side of the gunnel all come together. The spot is approx 4" diameter. I'm fixing to stick some auto bondo or similar on it and then mold/shape for the right contour. The question is how to be able to smooth it on with minimum surface roughness. There used to be a number of tricks for doing that, such as a paint stirrer paddle kept wet by dipping in water. Is this still the easiest way to be able to soft mold the patch and get it close to where it needs to be before I start shaping when dry? If I need to, I can finish it with glazing putty, before painting. Having read the other answers; it seems you're not going to re-glass the area just cosmetically fill the hole & then reshape & finish??? I guess you're happy there is no structural issue??? The deck to hull joint in way of the transom &/or outboard well is fairly highly stressed??? Anyway, (i) Use a polyester filler, it will adhere to freshly ground clean & dry polyester fibreglass OK. The filler has little real strength & if the area is structurally stressed & flexed it will crack etc. (ii) Experiment a little so you get the amount of catalyst just right, so it takes about 15 minutes before the filler starts to "gel" (you need to experiment a little because the amounts of micro balloon fillers in the resin can vary even from batch to batch & of course you need to adapt to your particular temps humidity etc) (iii) Do the filling in several stages, the first to well below the final level needed & each time let the filler just start to gel then shape it with a u profile surfoam blade (just hand hold it without the blade holder it's light & easy to manipulate, because the filler is the consistency of cheese or soap & will easily grate off in slices, if it doesn't you've let it cure too long & no amount of "sanding" will ever get a proper shape, so grind & re-fill) long smooth cross hatched strokes & look along the boat, corner etc to get it right. (iv) Once you have the filling & surfoam shaping up nearly to the final level, take a plastic filler applicator & cut small but deep "V"s along one edge (e.g.1/2" deep on a 1/4" base say 3/4" apart). Then apply a coat of filler & carefully scrape it off with the V'd applicator. This should leave you with nice parallel little ridges of filler. (the pros put a bit of tint in the ridges so they're a different colour to the other filler) (v) Once the ridges have gelled & cured a bit so they're strong enough not just to crumble, use a long board to sand in the "final" shape. Even though the ridges are relatively hard compared to the cheese of (iii) it shapes & sands very quickly & easily because you're only sanding skinny ridges. (vi) Once you're happy the shape is perfect then you can use a non V'd applicator to fill in between the ridges, then after it's cured (unlike the surfoam you can't sand filler if it's too soft, just clogs) start sanding with an orbital sander (no courser than 80 grit) & here's the trick, sand till you just start to uncover the tops of the final shaped ridges & no further (that's why the pros use tint, they can see it "through" the overlaying filler as they sand down). (vii) After you have that then start surface finishing with filler scraped into the 80 grips marks sanded off with say 120 then again scrape filler hard over the surface into the swirl marks & sand till all imperfections are gone. (viii) If you want to use gelcoat to refinish then put it directly onto the filler with that sanded surface, never ever try to put gel coat over a primer or "paint" (where does he get this stuff???:-)) (ix) The gel coat will not harden on the outer surface (gelcoat has no wax in it & you shouldn't ever add any either, but once you've put it on & it's just started to gel cover it with cling wrap or even paint on PVA water soluble release agent (this does the same as the wax & seals the gelcoat from the air so it can cure full depth. (x) Peel off the cling & sand with ever finer wet & dry, lots & lots of water & always with a little sanding block (i.e. do not sand it with hand held wet & dry, you will not get a good shine at the end) (xi) Machine with cutting compound & if the colour of the gelcoat is a good match you'll be proud of it. K |
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