I've got an 11 yr old non-porcelain tub that has had a couple hairline cracks in the base of it. These don't leak but I think I should do something to get rid of the structural weakness that this sets up, before the cracks widen.
I've got some white Bondo that I recently used for an exterior wood repair job. All the repair info I've seen on this stuff has putting in some fiberglass "netting", and then applying the epoxy stuff. I doubt that's necessary for dealing with a hairline crack.
Do you know the manufacturer of the tub, or even what material it's made of?
I'd phone the 1-800 Customer Service phone number of any company that makes the same kind of tub to see what they recommend. It's going to be difficult to find a material that will stand up to being submerged in water much of the time, and still make the repair smooth enough to be acceptable in a bathtub.
Also, those hairline cracks might not be deep enough to pose any real danger of the tub leaking. You might be able to eliminate the appearance of those cracks simply by cleaning the tub with oven cleaner, which I don't believe will harm anything except aluminum, so if you have aluminum shower door frames, keep the oven cleaner off of them.
What I'm thinking is that the cracks may look much worse than they are simply because they're black and stand out against the light coloured plastic of the tub.
Soap becomes soap scum because hardness ions in your water cause multiple soap molecules to coalesce around a single hardness ion. Since it's the ionic end of the soap molecule that attracts polar water molecules, having multiple soap molecules surrounding a single ion causes that assembly to lose it's solubility in water. That is, soap scum is simply soap that's lost it's solubility in water.
By introducing oven cleaner, (NaOH), you greatly increase the number of Na+ ions, which drives the chemical reaction in the opposite direction. That is, soap scum molecules break down to form soap molecules and hardness ions, and the soap molecules clean up easily because they're soluble in water.
I'd put a bit of oven cleaner on your worst affected area and see if it at least improves the aesthetics of your tub. You may find that having done that, your tub isn't really any worse than anyone else's tub of the same vintage.
If it ain't broke, don't try to fix it. You may cause a much worse looking tub. I would try to rub some white paint into the cracks to minimize their appearance, but not try to patch it.
Acrylic tubs aren't strong. A good installation has a bed of plaster or concrete under the plastic. If it isn't properly supported, it's likely to flex and eventually crack. Sometimes you can get access to see what's underneath.
They make special expanding foam for tubs that aren't properly supported, if there's a floor underneath. You drill 1/4" holes in the area around the crack and inject the foam. Then you sand it flush.
You drill a 1/4" hole at each end of the crack to stop it from continuing. Then you fill the crack and those two holes with 2-part polyester. You sand that nice and smooth. Then you get a spray can of bath tub paint that's the right color. Keep applying coats until you like it.
How do you fill a hairline crack with the 2-part polyester?
What I've read about Bathtub Refinishing Epoxy Paints, like the Klenck's product Home Depot sells, or used to sell, is that it's hard to get a smooth finish with them because the paint is thick and leaves terrible brush strokes. How do the people that do this kind of work paint the tub? With a roller, or do they spray the epoxy paint on or do they actually use a brush?
Before epoxy - if it were me - I'd apply some cyanoacrylate glue (super glue). Not much, just enough so that it would wick into the hairline crack. CA will slightly soften some plastics but once it cures the plastic returns to its former state.
I'm wondering how you have hairline cracks that don't leak. Is it possible that they're just deep scratches? If they're really cracks then it's time to remodel the bathroom. One doesn't just glue bathtubs together. If water gets through that you don't know about you could eventually be faced with a bigger job than the tub: Replacing the floor joists and the ceiling below.
| 2. What I've read about Bathtub Refinishing Epoxy Paints, like the | Klenck's product Home Depot sells, or used to sell, is that it's hard to | get a smooth finish with them because the paint is thick and leaves | terrible brush strokes. How do the people that do this kind of work | paint the tub? With a roller, or do they spray the epoxy paint on or do | they actually use a brush? |
They spray it. I've seen it done many times and it usually looks pretty good, but it won't cover scratches and dings in the old finish. It settles down so well that even tiny scratches will often show through. So the final look depends a lot on the smoothness of the underlying porcelain. (Tiny grit scratches in the bed of a tub aren't noticeable when it's dull, but they stand out when a new, glossy finish is put on.)
Painting acrylic, though, doesn't seem like a solution to me. When they spray porcelain they first etch it with acid. Also, plastic probably flexes quite a bit more than a steel/cast iron tub, making it difficult for a top coat to stay stuck. I wouldn't try anything like that on plastic unless it's especially designed for plastic.
| 2. What I've read about Bathtub Refinishing Epoxy Paints, like the | Klenck's product Home Depot sells, or used to sell, is that it's hard to | get a smooth finish with them because the paint is thick and leaves | terrible brush strokes. How do the people that do this kind of work | paint the tub? With a roller, or do they spray the epoxy paint on or do | they actually use a brush? | They spray it. I've seen it done many times and it usually looks pretty good, but it won't cover scratches and dings in the old finish. It settles down so well that even tiny scratches will often show through. So the final look depends a lot on the smoothness of the underlying porcelain. (Tiny grit scratches in the bed of a tub aren't noticeable when it's dull, but they stand out when a new, glossy finish is put on.)
Painting acrylic, though, doesn't seem like a solution to me. When they spray porcelain they first etch it with acid. Also, plastic probably flexes quite a bit more than a steel/cast iron tub, making it difficult for a top coat to stay stuck. I wouldn't try anything like that on plastic unless it's especially designed for plastic.
That was my thought also. Cracks never seem to stop unless drilled so it will only get worse.
Do you use the tub for baths? If so, replace it, but if not, you can buy a shower pan the same size and have a really nice walk in shower. I did one bathroom last year and the second is being tiled as I write this. This is what I used
I suspect it is crazing feom flexing. Usually has to get pretty bad before it leaks, but don't leave water standing in the tub for days!!!
When I install a "plastic" tub I make sure it is well supported. Last one I did I put high density foam board under the tub then sprayed itin with high density urethane foam. Salid as a cast iron tub. No flex at all.
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