[sacovington]

I know this topic has been covered several dozen times, but I've still got questions about coloring the LR.

I'd like to color the portland/crushed-coral mixture with cement pigment (or food dye??) to visually "age" it but I don't know what types are safe for the aquarium. Anyone used pigments? Recommendations? I've read a ton of posts on this all over the Net but everyone who's done it just says "i used cement pigment" -- they don't say what kind.

Thanks in advance for your advice!

[pogodzib]

I've experimented with aragocrete , but have never tried any artificial coloring. The rocks age and get covered with coralline fairly quickly so I think most people don't worry too much about the color.

[H2Oasis]

We have done a few thousand pieces of rocks both with and without colorant.

Cement additives work good as long as you can get the powdered versions. The liquids are a little too thick and have a tendency to clog up most of the rock and defeating the purpose of aragocrete partially.

We have some small packets of colorant we sale after buying in bulk because the stuff is quite expensive for anything other than browns, reds or black. We have blue, green, pinkish and purple, and a slight yellowish tint color.

Hope that helps ya out some..............

Bill
Mix's & Supplies : H2Oasis Supply House!, Custom LED Lights and Sump Filteration

[sacovington]

H2Oasis-
Thanks for the info :-)

Just curious though, i've read some posts mentioning the use of vinegar to speed curing time. Anyone tried this? How much would you use? Is it safe?

[H2Oasis]

After over 5 years of making these rocks, we have found no evidence that vinager or any other additive will speed up the curing process. Unfortunately it seems that cement cures like cement and any other cement no matter what is added to it. Its a chemical process wich takes place, and im sure that if there was such an item that thousands of multi-million dollar companies that create concrete or cement structures would be using it. But alas there is not any such critter, wich can be verified at the actual cement makers website.(such as portland or whatnot)
However, it does ad in cleaning of the cement and giving it a bit of an etched effect, but this is something you get naturally from curing anyway if you wait long enough.

So as far as im aware of there are no shortcuts that work for curing aragocrete. Ive heard of several, but have never seen any of them verified or validated with any proof. So for us its purely just wait and wait. Besides, I wouldnt want to put any of my critters in harms way (much less someone else's) because I become impatient.

Bill

[pogodzib]

Some people use vinegar to help speed up the process, but if you think about what vinegar does (dissolve calcium), is it really something that you want to be adding to speed up the curing process. In all reality, the aragocrete is curing both on the outside surface and deep inside and the vinegar doesn't help speed up the internal portion very much. Vinegar is fine to use in a reef tank, within reason, since the vinegar is being added into water that is full of calcium. In your aragocrete curing, the water doesn't have calcium in it except for the calcium that has left the homemade rock. I'd suggest using the same philosophy as everything else with reef tanks - go slow and be patient.

[Smiley1]

the best way to speed up the curing is to make sure your portland cement is mixed/dissolved thoroughly before you start adding your aggregate. As far as coloring it, i wouldnt waste your time or money on it. Most color additives will bleach out ove r aperiod of time anyway. You could add plastic shavings to give color specs to it but it will all be covered in coraline in a short time anyway. If you use rock salt in your mixture as well as for the molds, you will end up with lots of holes and very porous surface on the rock. Although it will take a little longer to cure all the rock salt out of the center of the rock.

[H2Oasis]

As Smiley1 stated, premixing all the dry ingrediants is extremely crucial.
And rock salt does indeed make the rocks very porous, however it also weakens the rocks or any cement for that matter. If you use rock salt at all, ensure its only for decorative pieces and not for rocks that would be weight bearing or on the bottom of a pile.

We have used 1/4" solar salt on several occasions, but only as decorative pieces, or large pieces that will be the only rocks within the tank.

Bill
H2Oasis

[Smiley1]

i don't know about weakening it..... every rock i made using rock salt was so hard, i couldnt even break it with a hammer.....if you use the right mixture of portland cement, sand, and other aggregate, mix it well, then add the rock salt, you should have absolutely no change in the strength of the rock. I used a mixture of 1 part portland cement (screened so there was no clumps) , 1 part reef sand, 2 parts crushed coral and mixed it well. the consistance was just wet enough to hold the mix together but not very wet... then added 4 parts solar salt.

[H2Oasis]

Rock salt or any salt for that matter, in its very nature expands when wet. Within the confines of cement mixtures, like aragocrete it can if fully encapsulated cause cracking in the cement as its curing. Reason is, as the water evaporates from the rocks during curing the cement naturally shrinks in size, while at the same time salt is expanding, wich in turn can cause internal cracks thruout the rocks.

While your chances of this happening are very slim, and you may be willing to take the chance.

Ive however, after making several thousand rocks over the years, have seen it happen.

I personally wouldnt add one of these rocks on the bottom of a rock pile or holding anything up with any type of weight load on it. And if we get a client that wants a rock created utilizing salts of any type, we have them sign a waiver of release for incidental damages for further down the road.

Any doubts, there is a ton of information available to the general public at the portland cement associations website, research papers, and much much more that covers almost anything you can dream of for use with cement.

As for the vinegar, its never been shown to reduce cure times and we have tested this one. Works more like an outer surface cleaning than anything, but no shortening of cure times.
As for colorants, if the proper colorants are used, and then cured correctly, they will last the lifetime of the rock. However in an aquarium most of the natural rock colors get coated with their own life forms anyway.

[Smiley1]

guess i must have been sick the day they covered concrete in the construction materials and theories class. Besides, in a 40g tank i doubt he will have enough weight to even matter.