As a novice I’m constantly figuring out how many drops or CCs of catalyst I need depending on the amount and type of resin I’m using. I got tired of it so I made a table to cover most scenarios. I thought I’d put it up here incase anybody else might want to use it.
I hope it uploads and downloads right.
<<< EDIT >>>
I updated the pdf. file to increase the catalyst dosage for gloss resin and I added the catalyst % by volume.
Note: It’s interesting that after doing the calculation the dosage in Drops/oz. is roughly the same as the % by volume times 10. Handy coincidence eh?
Any words on how 8 or 10 or 12 etc. drops per oz changes working time or is used in different shop temperatures?
For example, my little thumbnail chart - that provides basically the same amount of working time in each version - is 10 drops/oz at 90F, 15 drops/oz at 70, 20 drops/oz at 50*…
I figured I’d put it out there in case anyone found it useful. I take from here more often than I give so it’s the least I can do. It’s not much, but it’s what I got.
I’d say loosely that 8, 10, and 12 drops get me about 20 minutes at 80, 70, and 65 degrees. Roughly. But whatever the drops per oz., I get tired of refiguring drops and CCs for the amount of resin I’m using. Hence the table.
Good point though. I haven’t been very methodical about comparing gel times to temp, resin, and cat’ dose. I’m gonna get a thermometer for the garage and start taking samples of every batch I make. Wouldn’t take much. A little bathroom dixie cup, write time and temp on the side, pour a 1/8" sample, have a little log near by, tip it ever couple of minutes, easy as pie. Had I been doing that over the last year I’d have the some good numbers to put into the table. Mabye it’s a chart with temp (y) and dose (x), make it scattar plot with a line of best fit for each 5 degree temp range. Oooh aaahh. Let the data collecting begin.
I’ve had some trouble with gloss. I’d say everytime I’ve under catalyzed. At first I didn’t know it needed so much more cat’. The first few times I catalyzed on the higher side of what I would with hot or lam’ resin. That took for ever. Literally hours. I got slabbing on my gloss coat which made for a lot more sanding. I’ve moved up on the dosages. Last night I put in 23 drops per oz. on a 14 oz. batch. That still took about an hour before it gelled. That was at about 65F in SoCal. That’s the most cat’ I’ve used in gloss so far. I’d still use more next time unless it’s a lot warmer. I’ve heard stories of gloss being kicked too hot and getting heavy orange peel effect. I’ve been trying to avoid that. As long as I’m not in a hurry, I’d rather give it time to really flow out, as long as it sets in a reasonable time, than rush it and get a thick orange peel coat.
The gloss I used was Reichold from Crystaliner in Costa Mesa. If you’ve got resin from another manufacturer you might want to do a test batch.
There are some good threads here on applying gloss. You might want to search it. Basically, get it on quick, use a good brush to spread it lengthwise from the inside out, cross stroke the whole thing, then really light nose to tail stroke over the whole thing and walk away. The quicker you get it level, the smoother it will be.
Howzit Ryan, Environment makes for a big difference when it comes to catalyst amounts. An example is I did laminating on the East side of Kauai in the 80’s and about 6 cc’s cat for a quart of resin was the ideal amount. Now in the Hanalei area it was 12 cc’s per quart of resin for laminating. For glossing resin I use about 25 cc’s for 20 ounces of gloss in Hanalei ( no gloss work on East side). What brand of glossing resin are you using,Sylmar or Rhiechold. Big difference between the two. Sylmar kicks really slow and Rhiechold kicks faster. Doing gloss in clod weather doesn’t help either. There was a time when you could get cobalt which would make resin kick faster but I’m not sure it’s available any more due to it’s toxic content. A good gloss should start kicking at about 10 minutes after last brush strokes. Aloha,Kokua
Yah, I try to account for temperature. I’m learning as I go. I suppose in a temperature controlled room it would be a lot easier. I called Crystaliner and they said the gloss is Rheichold. They had warned me that it takes a lot more catalyst. I used just short of what they recommended and it took too long. Supposing their recommendation is for normal temps, like 70 or so, they probably gave me the right dosage. I used just short of what they said and it was mid 60s and it took a little longer than I would’ve liked.
Dan,
Give them a call. Anybody carrying chemicals should know who the manufacturer is. If they say they don’t know, ask them to check the MSDS (material safety data sheet. Either way, you probably should do a test batch. Start around 25 drops/oz.
Thanks for you help Ryan. Epoxy is all I have done until now. I finally managed to get in touch with Basham’s and they carry Reichold so I think I’ll start at the 25 drop rate.
I can’t see your table for some reason (sounds like others can)… but I can’t see counting out 25 drops/ounce x 14 ounces of resin. Why don’t you just get a bodhi bottle (catalyst dispenser), it’s WAY easier and plenty accurate for anything but the tiniest amounts…
On his table he has it broken down like you said. Where he’s using the term Drops actually looks like different temperature mixes (ex. 20 drops = hot weather). I was hoping that I was going to be able to make it down to your event, but things didn’t pan out. I could have used a little schooling in how to play with poly
Yah, it would help if you could see it. It’s a simple table with columns grouped by dose. In other words, for every resin amount it shows the dose in both drops and CCs. That way you can chose when you’d rather count or measure. With a bodi you still need to know how many CCs you want to use in relation to the amount of resin. I don’t have a bodi. I have little cups, like cough syrup cups, with CC measurements on the side. Same idea.
In my mind I think of dosing in terms of drops per oz. Since I don’t like counting rediculous amounts of drops I’d convert to CCs. Doing that math got old so I made the table for quick answers.
ok, yeah, now I see what you’re doing. The chart I use has various % levels in columns, similar to yours but uses e.g. 0.5%, 0.75%, 1% rather than 10, 12, 14 drops/oz. I just almost never mix such small quantities that I would think in terms of # of drops…
I guess I’ve trained myself to think small because I’ve only done repairs so I make lots of small batches. I done some big lams on longboards and full sand and regloss so I’ve done some decent batch sizes but I think in terms of drops.
Maybe when I make a few boards I’ll start thinking in terms of percentage.
I guess I’ve trained myself to think small because I’ve only done repairs so I make lots of small batches. I done some big lams on longboards and full sand and regloss so I’ve done some decent batch sizes but I think in terms of drops.
Maybe when I make a few boards I’ll start thinking in terms of percentage.
Howzit Ryan, Rheichold kicks off faster than Sylmar and I use Rheichold which is what F.H. sells for glossing resin. Get yourself 1 of those little plastic catalyst measuring cups that holds about 1 ounce. It has cc measurements so you don't have to use drops. Unless i'm doing boards I just eyeball the measurements, but for boards I use the measurement cups and for glossing I use 25 cc's for about 20 ounces of glossing resin plus I add styrene and some S.A. and both of these slow down the kicking time so if you arent adding these to your gloss resin it should kick even faster (not a good thing since the gloss resin won't have time to flatten out). Go to the archives and get my formular for glossing resin and the additional % of the styrene and S.A. added to the mixture. I usually gloss when the temperature is around 75- 80 degrees so you might need to add even more catalyst to make up for lower temps.Aloha, Kokua
I used Reichold last month for the first time. I was doing a Bonzer. It kicked halfway through the bottom lam. I was seriously pissed off, given that I thought I had a really clean shape.
