Which sanding discs?

fisherman

fisherman

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I have some damage to fill and fair, using epoxy gelcoat filler, and then want to flatten the hull for painting with Perfection. (been coated already). On the random orbital sander, Aluminium oxide perforated discs or silicon carbide unperforated? Or something else? I've always preferred wet n dry in the past.
 
fisherman said:
I have some damage to fill and fair, using epoxy gelcoat filler, and then want to flatten the hull for painting with Perfection. (been coated already). On the random orbital sander, Aluminium oxide perforated discs or silicon carbide unperforated? Or something else? I've always preferred wet n dry in the past.
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My opinion

These discs:
http://www.axminster.co.uk/fixing-g...sch-velcro-backed-abrasive-discs-150mm-6-hole
and I recommend one of these:
http://www.axminster.co.uk/abrasive-belt-cleaner-standard-210-x-40-x-40
Abrasives typically become clogged before they wear out. Sanding one of these cleaning sticks cleans them and prolongs their life. I use them all the time.

I like Axminster for their completeness and knowledge. If there is interest in this thread someone will tell you a cheaper supplier.

I assume your love of wet and dry doesn't extend to electrocuting yourself by using a mains sander wet.
 
Use 3M or Mirka freecut discs perforated to suit your sanders pad and use a vacuum cleaner (henry type) with long hose connected to your sander. The vacuum will prolong the life of the disc and prolong your life as well. Depending on your existing finish use 180/240/360 grit discs. Aluminium oxide are not suitable for this sort of work.The finer you go down to the better the ultimate finish. This is the system I use as a professional yacht painter. I have rarely seen wet & dry used professionally these days as the alternatives are better and produce a lot less mess.
 
itchenseadog said:
Use 3M or Mirka freecut discs perforated to suit your sanders pad and use a vacuum cleaner (henry type) with long hose connected to your sander. The vacuum will prolong the life of the disc and prolong your life as well. Depending on your existing finish use 180/240/360 grit discs. Aluminium oxide are not suitable for this sort of work.The finer you go down to the better the ultimate finish. This is the system I use as a professional yacht painter. I have rarely seen wet & dry used professionally these days as the alternatives are better and produce a lot less mess.
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Thank you, did a lot today and looking hopeful, got rid of the runny paint from last time, still a lot of flattening out to do. Would you recommend perfection, bearing in mind it has been used already, or some other? Of course this is a fishing boat, will be hand painted not sprayed, and not expected to look like a million dollars, but £9.50 would be good.
 
fisherman said:
Thank you, did a lot today and looking hopeful, got rid of the runny paint from last time, still a lot of flattening out to do. Would you recommend perfection, bearing in mind it has been used already, or some other? Of course this is a fishing boat, will be hand painted not sprayed, and not expected to look like a million dollars, but £9.50 would be good.
Click to expand...

Depends on what you want and what you can afford. For a durable lasting finish use a 2 pack such as International Perfection. However, if its a fishing boat thats likely to get lots of knocks and you're happy to repaint more often, why not use a single pack paint such as International Toplac. You can use single pack on top of two pack but not the other way round.
A tip that I was given as an apprentice by ths then owner of Blakes Paints is as you apply the paint, tip off with a brush vertically rather than horizontally as the paint will flow into a smoother finish. It is a tip that has served me well during the course of my career.
 
I think last time I used a roller then a sponge brush, vertically as you say, it was the temperature as well as lack of prep more of a problem. Thanks for the advice.
 
itchenseadog said:
Depends on what you want and what you can afford. For a durable lasting finish use a 2 pack such as International Perfection. However, if its a fishing boat thats likely to get lots of knocks and you're happy to repaint more often, why not use a single pack paint such as International Toplac. You can use single pack on top of two pack but not the other way round.
A tip that I was given as an apprentice by ths then owner of Blakes Paints is as you apply the paint, tip off with a brush vertically rather than horizontally as the paint will flow into a smoother finish. It is a tip that has served me well during the course of my career.
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Sorry, here I come picking your brain again: Perfection, Jade Mist green, quite dark, they recommend using white undercoat. Yes? With some colour added? Boat is more or less that shade already, and I've used pigment in the filler. At the 320 grit stage today.
 
fisherman said:
Sorry, here I come picking your brain again: Perfection, Jade Mist green, quite dark, they recommend using white undercoat. Yes? With some colour added? Boat is more or less that shade already, and I've used pigment in the filler. At the 320 grit stage today.
Click to expand...

Unfortunately, it looks as if International in their wisdom (?) are only allowing Perfection undercoat White onto the diy market.
Normally I would have used the dark grey but this and blue are it seems only available on the professional market. So without going cap in hand to one of the wholesale distributors, I would carry on with what you are doing and tone down the white undercoat with green topcoat. Don't be surprised if your first topcoat comes out streaky as it has a lot of colour change to cover. Perhaps that why International only have the white undercoat available so thay can rack up the sales of topcoat !
Post some pics on here to show the finished result.
 
This is where I struggle.

"Perhaps that why International only have the white undercoat available so they can rack up the sales of topcoat !"
Am I cynical? Yes.

I am covering a mix of rubbed down Perfection dark green and original dark green gel with white, and I know only too well how that will bleed through when I cover it with dark green again (trying to obliterate my reg numbers). Extra cost and work, plus waiting for the right atmospheric conditions. Hopefully it will be worth it. I will try to get hold of darker undercoat.
 
Amulet said:
My opinion

These discs:
http://www.axminster.co.uk/fixing-g...sch-velcro-backed-abrasive-discs-150mm-6-hole
and I recommend one of these:
http://www.axminster.co.uk/abrasive-belt-cleaner-standard-210-x-40-x-40
Abrasives typically become clogged before they wear out. Sanding one of these cleaning sticks cleans them and prolongs their life. I use them all the time.

I like Axminster for their completeness and knowledge. If there is interest in this thread someone will tell you a cheaper supplier.

I assume your love of wet and dry doesn't extend to electrocuting yourself by using a mains sander wet.
Click to expand...

Not sure how many you want but I ordered lots today from Southern Filters.

They advise that Sia disks are now more popular than Mirka. The DA sanding machines and disks that a neighbouring boat kindly lent me were Sia. He "borrowed" this equipment from his workshops and said they found the disks the best P80 upwards they are Siafast. Obviously what the professional businesses use!

Ref the OP you need to determine whether just the gel coat is cracked or the GRP. Just had my boat desking repaired 4yrs after original impact. Original impact only visible damage was to internal joinery and 100mm square area of hull. 4yrs later deck showing a series of longitudinal cracks extending some 5 ft long in a curved shape around impact point. Professionals sanded anti slip deck textured surface off over completed side width and about 8' long, relaminated fibre glass over deck then recast anti slip deck surface in gel coat.

From my experience of repairing Glass Fibre Cars (30yrs ago!) any surface cracking will always reappear if you don't repair the substrate. Gel coat repair only for a quick sale!!
 
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Just ordered some 320 grade DA sanding discs from Southern Filters and found their Director Becky very knowledgable and helpful.

In my case she recommended Sia discs instead of Mirka as they are a ceramic grit and last longer and block up less (Mirka are a grit based I believe).

They sell so many of various types to various trade they can advise.

I hate re-inventing the wheel when others have already learnt from experience!! I was so happy with the two Metabo DA sanders I borrowed last week that I have bought my own but I thought I would check with Becky and she quickly recommended another make (twice as dear thought!!) for boat work as she said working on the underside the weight of the DA sander is important hence she recommended one that is only 950g while the Metabo is 2200g!!

Unfortunately I have bought mine now and only contacted Southern Filters for the paper. Becky offered the light DA for a trial - she delivers FOC hamble on Tuesdays - so may take her up on the offer next year.

For those not very experienced in rubbing down between coats a good tip I leant when I resprayed cars is to rub the wet and dry paper over soap to lubricate/reduce the "sharpness" and give a smoother finish. If I had a bad result (often a run!) I could cut back with soaped 1200 grade and then Facela compound instead of rubbing down and spaying a new final coat

Live and learn!!
 
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