Restoring a fiberglass(?) sink

[Don_ih]

It's fibreglass and it has way too much damage to the gelcoat.

It's possible to fix but probably too much work.

 

[mshchem]

Wash it . Use.

 

[BTC]

You could always go to Pittsfield and get this stainless one…

Darkroom Sink, Stainless Steel - photo/video - by owner - electronics sale - craigslist

For sale is a Stainless Steel custom made darkroom sink. The sink is approximately 54” x 23” and is 6 inches deep. The sink has a flat bottom and easily accommodates 3 large trays for 11 x 17 inch...

westernmass.craigslist.org

B

 

[Michael R T]

Well, this is what it looks like after pressure washing:

See the difference? Me neither.

Well, maybe I will have a sink with a lot of character, as some have suggested. The folks at the construction company next door have offered to spray it with some Red Hot degreaser, so we'll see if that does anything.

The flaking sections didn't seem to be affected at all by repeated sprays, so they seem quite strong still. I have yet to test for water fastness, though.

I did notice there are a couple sections on the underside which are lighter-colored and seem to have fibers exposed. Do these need to be patched/reglazed?

 

[Michael R T]

It's fibreglass and it has way too much damage to the gelcoat.

It's possible to fix but probably too much work.

I think the flaking is only happening in one section; is that the damage you're referring to?

You could always go to Pittsfield and get this stainless one…

Darkroom Sink, Stainless Steel - photo/video - by owner - electronics sale - craigslist

For sale is a Stainless Steel custom made darkroom sink. The sink is approximately 54” x 23” and is 6 inches deep. The sink has a flat bottom and easily accommodates 3 large trays for 11 x 17 inch...

westernmass.craigslist.org

B

I saw that, thank you! I have come across a few 4-5 foot sinks like that one, but I was looking for a 6-7 foot one, like this one.

 

[mshchem]

Don't use anything like degreaser. I would try a Mr Clean magic sponge on a small area, see if it's on the surface. That's a really nice sink. Under safelights you won't notice stains. If it's just the surface, and it comes off I would work on it after you have a stand, plumbing etc.

 

[Hassasin]

I'd try to send down the damaged gel coating, mainly to see what it takes to take off the layer down to fiberglass base. Orbital sander with grid 40/60 first, if that proves too aggressive switch to 80. It may not be too bad to get down to healthy base.

 

[mshchem]

I'd try to send down the damaged gel coating, mainly to see what it takes to take off the layer down to fiberglass base. Orbital sander with grid 40/60 first, if that proves too aggressive switch to 80. It may not be too bad to get down to healthy base.

I wouldn’t start with anything coarser than 400 grit, but I would try something like BonAmi powder (impalpable feldspar, scouring powder) . If it is stained through, use it unless you're like me spend more time building darkroom than using.

 

[Hassasin]

From the looks of it there are signs of total gel coat breakdown, so 400 grit is going to massage it more than remove it. Spatula will probably remove some of that too. If flakes can be removed, then the whole surface can be smoothed out and new coat can be applied, special marine paints are available to do just that.

Given shown condition, I would not put it to use unless I can lift off all the loose stuff completely. As is, flushing all chemicals would prove impossible.

 

[mshchem]

From the looks of it there are signs of total gel coat breakdown, so 400 grit is going to massage it more than remove it. Spatula will probably remove some of that too. If flakes can be removed, then the whole surface can be smoothed out and new coat can be applied, special marine paints are available to do just that.

Given shown condition, I would not put it to use unless I can lift off all the loose stuff completely. As is, flushing all chemicals would prove impossible.

I agree, but getting out 400 grit scratches is easier than 40 grit . Maybe start with 120 if you are adventurous. If it cleans up easily then refinishing could be avoided. Sounds like it is nice enough it could be sanded and have new gel coating applied but that's quite an undertaking. Buy 3M sandpaper

 

[Don_ih]

400 grit sandpaper is useless for sanding - it's only good for finishing. Using anything finer than 180 is just wasting your effort. The surface of that sink needs to be removed.

I think the flaking is only happening in one section; is that the damage you're referring to?

Yes - flaking is the step past crazing (which is likely happening to all of it).

This looks like damage from impact and probably not much of a problem.

Since this isn't going to be your kitchen sink or your bathtub, you could just scrape off whatever comes off easily and give it a coat of bathtub paint. A darkroom sink doesn't need to be beautiful to be useful.

 

[Snoop]

Thanks for all the replies! I've been working on finding a friend with a power washer, so I'll get back to you with photos when it's hopefully more cleaned up.

In the meantime, here are some closeup photos of the underside to give you a better idea of what the material looks like:

Under better light, I also noticed the top has a surface layer that is cracking or flaking off in places. In some places, the flakes can be removed, but in others it seems pretty tough and even though it's cracked they can't be pulled off by hand. Is this the glaze of the fiberglass (if that's what it is)?

Michael, when it comes to glass fibre you have two main groups, the cloth and the mat. What u see in the sink is mat
Wherever you find fiberglass products with mat you know the resin used is polyester resin (mat is not prepped for epoxy so they dont work well together)
What covers it is gelcoat
Old poorly kept or mistreated gelcoat can look all cracked like that, its not a big deal.
So what you have is a decent very likely polyester resin sink with some less decent gelcoat layer.
To repair (if there are repairs to be made) you have choices in resins: buy some polyester resin patch like some auto repair kit or buy some epoxy resin repair kit (know that epoxy will adhere very well both on polyester and epoxy resins, polyester resins will adhere well only on polyester resins). BTW working with epoxy resins is a fraction more expensive but much more pleasant and easy than with polyester, and you can use the resin for a lot of other things.
To repair a gelcoat that is dusty and flaking off you should remove the old and recoat it, if its just cracked but not weak then you can simply scrub it well with scotchbrite and recoat it.
Powerwashing wont tell you how much flakes off, some can hold on very well just because gelcoat is thick so its locked by everything else around, you can use a pick to see if flakes come off or if they are just cracks, but if the edges along the cracks are raised then that part isnt attached underneath anymore
If you wanted to really take most of it off there are abrasive pads that go from coarse grade to finer which you can put on a drill to get the work done really quickly, sandpaper clogs way too fast. You can do 80 grit easily, if the new recoating is to be rolled on it will go in a thick layer.
If you were to sand using sander or drill: the fiberglass is softer than the gelcoat so be careful not to go right into it.
Your choice for recoating the crackly gelcoat is either some other gelcoat or other types of paints. What is generally called gelcoat is polyester and iffy on epoxy resins, so if you made repairs with epoxy be warned, there are epoxy "gelcoats" on the market but if you dont specify when you buy it you are gonna end with the polyester stuff (of course if u didnt put any epoxy on it and dont see any unknown patches put on by other people you dont need to worry) Other types of paint are epoxy paints, acrylic or 2part polyurethanes, they are all quite tough and resistant
There are epoxy coatings for sink and bathtubs that will cover that sink nicely (as suggested by Don_ih) and I know they have been used for lab sinks and lab counters too so shouldnt be a problem in a darkroom, they are also quite easy to use.

As long the sink is solid, when you press on it there arent weak spongy spots, you shouldnt need to do any repair, if the old gelcoat is dirty but just crackly and not falling off you dont really need to eliminate it for recoating.

Dont be scared by the work, its not a lot, had to deal with boats in worse conditions than that sink, its just quite dirty and neglected.

PS: the black stains in the pics look a lot like whats in the tubby I use to clean motor parts, I can clean it only with industrial degreaser... you might wanna make sure its not grease, or sanding will only spread it further into the surface and recoating would be a failure

 

[Snoop]

I agree, but getting out 400 grit scratches is easier than 40 grit . Maybe start with 120 if you are adventurous. If it cleans up easily then refinishing could be avoided. Sounds like it is nice enough it could be sanded and have new gel coating applied but that's quite an undertaking. Buy 3M sandpaper

400 will clog way before being worn out. If it gets recoated gelcoat layers are relatively thick so you dont need the finish you would have under spray paints or varnish.
Think more working on a fiberglass boat rather than working on a car

 

[jeffreyg]

As I mentioned I coated a plywood sink and countertop 48 years ago with marine polyester and have had no problems with it. I just wanted to add that I added a color to it when I mixed the accelerator with the base material. I think there should also be one for epoxy. That way you will have a fresh new look.

 

[Paul Howell]

If the cracks are deep, once you've power wash it, you might need a can of resin to seal the cracks.

 

[mshchem]

As I mentioned I coated a plywood sink and countertop 48 years ago with marine polyester and have had no problems with it. I just wanted to add that I added a color to it when I mixed the accelerator with the base material. I think there should also be one for epoxy. That way you will have a fresh new look.

Testimony!! Polyester is very tough stuff. To the OP, depends on what you want to do, restore a sink, or use it? That's a nice sink, clean it up and refinish it.

 

[eli griggs]

What would be needed, besides a good cleaning for someone to take this sink and use it as a mold for making their own fiberglass copy?

 

[maltfalc]

sandblast it, work a coat of epoxy deep into those cracks with a foam roller, wet sand with a sanding sponge to smooth out any rough spots or raised edges of cracks and roll on at least one more coat of epoxy.

or you could get a big sheet of white polystyrene meant for tub surrounds and vacuum form it to the sink.

 

[darkroommike]

Yup, that's fiberglass, the top coat is called a gel coat and can be repaired or overcoated. It won't win a beauty contest but it should hod water.