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-   -   Problem with melamine mold bubbling-concrete counter top (http://www.diychatroom.com/f105/problem-melamine-mold-bubbling-concrete-counter-top-154742/)

lmeraw 08-24-2012 05:33 PM

Problem with melamine mold bubbling-concrete counter top
 
We followed the CHENGE book and DVD process and just demolded our first two countertops and they are prefect except.... The beautiful surface is pitted all over! The melamine base wetted and bubbled during curing leaving us with these pits. We are not planning to grind the surface; we were only going to polish... and we were 'lucky' to have almost no pinholes on the beautiful chocolate surface! I think the pits would mean a lot of material removal even if we did grind though. I'm afraid that a slurry would be difficult to level, and would it adhere in these rounded pits? What to do? Why did this happen? Our concrete was not at all runny. Please help!

oh'mike 08-24-2012 05:49 PM

I added to your title to attract more attention.

If you could post a picture, I'm sure someone will have a suggestion.--Mike----

gregzoll 08-24-2012 05:58 PM

How did you vibrate the slab? Where did you get the Melamine from, and do you have pictures of both the mold & the counter?

lmeraw 08-24-2012 06:06 PM

2 Attachment(s)
Attachment 56245

Here are the photos. The sides of the mold and countertop are fine. It's just the bottom (to f counter) that have these pits. Ugh! Melamine from Home Depot @ $30 per sheet! Will a slurry fill and adhere? Is this time-sensitive now in terms of my options?

Canarywood1 08-25-2012 06:32 PM

Quote:

Originally Posted by lmeraw (Post 995646)
Attachment 56245

Here are the photos. The sides of the mold and countertop are fine. It's just the bottom (to f counter) that have these pits. Ugh! Melamine from Home Depot @ $30 per sheet! Will a slurry fill and adhere? Is this time-sensitive now in terms of my options?


Slurry needs to be applied while the concrete is still green,like within a day or two of it being poured to adhere.

gregzoll 08-25-2012 06:42 PM

Has nothing to do with the Melamine that was used, it was how it was poured, and that the product was not vibrated for the right amount of time, then left alone. If I had a fair guess, I would have to say that you over vibrated or did not use a dry enough mix, and had too much water in it, which caused air bubbles to form.

The best thing to do, is when you do something like this, start small, then once you are comfortable with doing it, then proceed with the larger product. Bad thing is, you may have to do a repour and take time.

lmeraw 08-25-2012 07:13 PM

Hmmm. Well, I don't think that the pour wasn't dry enough. I was worried about the opposite....more like gooey mashed potatoes than anything that actually poured out of the mixer. I do wonder about the over vibrating though. We had a rod vibrator, and the concrete came out of the forms really nice... Not a lot of pinholes. Would over rotating make it too wet at the bottom of the mold. Other sources we talked to have said that the melamine shouldn't have bubbled like that... Like under a kitchen sink with a leaky faucet. Cheap melamine? We will get it from a cabinet maker source next pour, but I am still curious about the over vibrating possibility.

cabinetman 08-25-2012 08:20 PM

I'm thinking it could be a few problems. Not all melamine sheets have a smooth surface. Even a first class sheet has somewhat of a mottled finish...not slick, but an itsy bitsy dimpling pattern. Could be this sheet had deformations in the melamine surface, or had contaminants in the affected areas.

The concrete mix could have been out of ratio, or poorly mixed creating areas of poor consistency. Vibrating should remove air bubbles, and if the mix was too dry would account for pockets, bubbles that didn't make it to the top, and a surface less than slick.

The problem with doing a skim fill is that it's likely that the holes may become more prominent by not matching in color or texture.





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