Tag Archive: crack repair


TO:  Multi-Tech Products

I am trying to repair a hairline crack in a vitreous china (white Kohler K6652) service sink.  Which product would you recommend and what color white?
Thanks
Cindy
Cindy,

Unfortunately, a hairline fracture in vitreous china means there is a crack all the way through the fixture.  Vitreous china can be repaired and even glued back together with our colored Poly Paste product, and we have it in Kohler white.   However, the issue is how to get the Paste into the fracture.  Unless there are separated (broken)  pieces  than can be glued together, you would have to grind a “V” groove through the entire thickness of the sink.   Creating this “V’ groove would produce more damage to the surface than the original hair-line fracture, since it would be very visible.   Also, the back of the unit would need some kind of reinforcement to hold it together.  This procedure could be used if there is good access to the sink, but there are complications.

The repair would be complicated and require a refinish of the whole sink. The next question would be,  “should a service sink be completely refinished?”   The answer is no.  A service sink probably gets too much use and is exposed to damaging impacts, so a refinish would not last very long.  It could also be exposed to strong cleaning chemicals, which would cause the refinished surface coating to fail.

If it is sufficient to achieve a fix simply to prevent leakage through the crack, it could be repaired as described above. Be aware of the aesthetics limitations, and I would not give any kind of warranty.

Many things to think about. But, it is just wise to sometimes walk away from certain jobs. And sometimes, a technician needs to just make things functional too.

Hope this helps,

Rob

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TO: Multi-Tech Products

I recently completed a cosmetic damage repair on a shower wall surround. I used my standard repair filler, color coating and methods. The repair failed as the filler fell out of the prepared area while the coating bonded well. I remember not recognizing the material but proceeded with my usual methods anyway. It was a small crack and the structure was solid. When I used my grinder to prepare the crack, I found a material with two or three layers. It had different colors to the layers. The thin bath ware top white color, a pure white plastic like layer, and the structural layer similar to a composite reinforced structure. The structure layer did not smell like fiberglass when I ground into it some. What do you think it was, and what is the proper way to repair it so it will hold?

Thanks,
Steve
Dear Steve;

It sounds like you found a product made from what is called “co-extruded” in the industry. This material is less expensive than traditional materials and is becoming more popular in economy products. You will find them at your local Home Centers. Manufacturers continually seek materials and processes to lower manufacturing costs. Historically, most bath tubs and shower products have been manufactured from cross-linked, cast acrylic sheet or gel coat. Both are reinforced with FRP (polyester resin with embedded glass fibers). Cast acrylic sheet is the most expensive acrylic on the market, and the cross-linked variety was specifically engineered for bathtubs and spas. Therefore, it has the best balance of physical and chemical properties for these applications.

The co-ex product you experienced is made by extruding a two-layer sheet – the top is a lower molecular weight, un-cross-linked acrylic, and the bottom is ABS (acrylonitrile-butadiene-styrene copolymer). Typically, the sheet is .125″ thick with the top layer being about .025″ and the bottom layer about .100″. When formed into bathtubs or shower walls, it can then be reinforced with FRP, polyurethane (PU), or have no reinforcement. PU may have glass fibers in the resin, and it can be a high density foam or a smooth coating. Sometimes it is reinforced with fiberboard strips or panels.

You mentioned there was an odor when grinding the structure. This is usually the best way to establish identity of a polyester resin. Simply use sand paper (320 grit) to sand the material in question before proceeding with a repair. Grinding may be required to expose the different layers. Polyester resins will have a distinct sweet smell with sanding or grinding friction. After the sanding test to confirm that it is a polyester, it is safe to use similar polyester resins for filling and reinforcement purposes. If there is no polyester odor, use our binding resin for reinforcement. It is formulated to adhere to PU and other plastic surfaces.

We would also recommend verifying the structural strength and integrity of the repair zone before applying the color coatings. Be certain there is no movement or stress to the area when hand pressure is applied. If there is, remove any filler and start over with the repair.

When repairing the cosmetic surface of bath products made with “co-ex” , our materials and processes work well. Our MMA or Quick Glaze systems perform very well as the color coating. In fact, since the lower molecular weight acrylic is not cross-linked, coatings adhere to it better. However, compared to polyester resins, it is more difficult to achieve adhesion on ABS or PU. So, you should not use Poly-Filler or any polyester resin based crack or putty fillers. The deceiving factor is that most polyester fillers will initially bond to the material for a short period.   However, after time it will lose its adhesion to the ABS or PU, and will break away from the repair zone. Our acrylic filler should be used for this application.

I hope this provides you the necessary information to perform the best repair.  If you need more help, please call or email.

Thanks,

Rob Clos